GRBModel#
- GRBModel#
Gurobi model object. Commonly used methods include
AddVar
(adds a new decision variable to the model),AddConstr
(adds a new constraint to the model),Optimize
(optimizes the current model), andGet
(retrieves the value of an attribute).Objects of this class have unmanaged resources associated with them. The class implements the
IDisposable
interface.While the .NET garbage collector will eventually collect an unused
GRBModel
object, the vast majority of the memory associated with a model is stored outside of the .NET heap. As a result, the garbage collector can’t see this memory usage, and thus it can’t take this quantity into account when deciding whether collection is necessary. We recommend that you callGRBModel.Dispose
when you are done using a model (or use the .NETusing
statement).- GRBModel GRBModel(GRBEnv env)#
Constructor for
GRBModel
that creates an empty model. You can then callAddVar
andAddConstr
to populate the model with variables and constraints.- Parameters:
env – Environment for new model.
- Returns:
New model object. Model initially contains no variables or constraints.
- Example:
// Create environment GRBEnv env = new GRBEnv(); // Create model and attach it to environment GRBModel model = new GRBModel(env);
' Create environment Dim env As GRBEnv = New GRBEnv() ' Create model and attach it to environment Dim model As GRBModel = New GRBModel(env)
- GRBModel GRBModel(GRBEnv env, string filename)#
Constructor for
GRBModel
that reads a model from a file. Note that the type of the file is encoded in the file name suffix. Valid suffixes are.mps
,.rew
,.lp
,.rlp
,.dua
,.dlp
,.ilp
, or.opb
. The files can be compressed, so additional suffixes of.zip
,.gz
,.bz2
,.7z
or.xz
are accepted.- Parameters:
env – Environment for new model.
modelname – Name of the file containing the model.
- Returns:
New model object.
- Example:
// Create environment GRBEnv env = new GRBEnv(); // Create model from file myModel.mps and attach it to environment GRBModel model = new GRBModel(env, "myModel.mps");
' Create environment Dim env As GRBEnv = New GRBEnv() ' Create model from file myModel.mps and attach it to environment Dim model As GRBModel = New GRBModel(env, "myModel.mps")
- GRBModel GRBModel(GRBModel model)#
Constructor for
GRBModel
that creates a copy of an existing model. Note that due to the lazy update approach in Gurobi, you have to callUpdate
before copying it.- Parameters:
model – Model to copy.
- Returns:
New model object. Model is a clone of the original.
- Example:
// Create environment GRBEnv env = new GRBEnv(); // Create model1 and attach it to environment GRBModel model1 = new GRBModel(env); // ... // Update model before copying model1.Update(); // Copy model GRBModel model2 = new GRBModel(model1);
' Create environment Dim env As GRBEnv = New GRBEnv() ' Create model and attach it to environment Dim model As GRBModel = New GRBModel(env) ' ... ' Update model before copying model1.Update() ' Copy model Dim model2 As GRBModel = New GRBModel(model1)
- GRBModel GRBModel(GRBModel model, GRBEnv targetenv)#
Constructor for
GRBModel
.Copy an existing model to a different environment. Multiple threads can not work simultaneously within the same environment. Copies of models must therefore reside in different environments for multiple threads to operate on them simultaneously.
Note that this method itself is not thread safe, so you should either call it from the main thread or protect access to it with a lock.
Note that pending updates will not be applied to the model, so you should call
update
before copying if you would like those to be included in the copy.For Compute Server users, note that you can copy a model from a client to a Compute Server environment, but it is not possible to copy models from a Compute Server environment to another (client or Compute Server) environment.
- Parameters:
model – Model to copy.
targetenv – Environment to copy model into.
- Returns:
New model object. Model is a clone of the original.
- Example:
// Create environment GRBEnv env = new GRBEnv(); // Create model1 and attach it to environment GRBModel model1 = new GRBModel(env); // ... // Update model before copying model1.Update(); // Copy model and attach it to env GRBModel model2 = new GRBModel(model1, env2);
' Create environment Dim env As GRBEnv = New GRBEnv() ' Create model1 and attach it to environment Dim model1 As GRBModel = New GRBModel(env) ' ... ' Update model before copying model1.Update() ' Copy model and attach it to env Dim model2 As GRBModel = New GRBModel(model1, env2)
- GRBConstr AddConstr(GRBLinExpr lhsExpr, char sense, GRBLinExpr rhsExpr, string name)#
Add a single linear constraint to a model.
- Parameters:
lhsExpr – Left-hand side expression for new linear constraint.
sense – Sense for new linear constraint (
GRB.LESS_EQUAL
,GRB.EQUAL
, orGRB.GREATER_EQUAL
).rhsExpr – Right-hand side expression for new linear constraint.
name – Name for new constraint.
- Returns:
New constraint object.
- Example:
// Create variables GRBVar x = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "x"); GRBVar y = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y"); // Create linear expression x + y GRBLinExpr lexpr = new GRBLinExpr(0); lexpr.AddTerm(1.0, x); lexpr.AddTerm(1.0, y); // Add linear constraint x + y = 0 with name c1 GRBConstr constr = model.AddConstr(lexpr, GRB.EQUAL, 0.0, "c1");
' Create variables Dim x As GRBVar = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "x") Dim y As GRBVar = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y") ' Create linear expression x + y Dim lexpr As GRBLinExpr = New GRBLinExpr(0) lexpr.AddTerm(1.0, x) lexpr.AddTerm(1.0, y) ' Add linear constraint x + y = 0 with name c1 Dim constr As GRBConstr = model.AddConstr(lexpr, GRB.EQUAL, 0.0, "c1")
- GRBConstr AddConstr(GRBTempConstr tempConstr, string name)#
Add a single linear constraint to a model.
- Parameters:
tempConstr – Temporary constraint object, created by an overloaded comparison operator. See
GRBTempConstr
for more information.name – Name for new constraint.
- Returns:
New constraint object.
- Example:
// Create variables GRBVar x = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "x"); GRBVar y = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y"); // Add linear constraint x + y = 0 with name c1 GRBConstr constr = model.AddConstr(x + y == 0, "c1");
' Create variables Dim x As GRBVar = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "x") Dim y As GRBVar = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y") ' Add linear constraint x + y = 0 with name c1 Dim constr As GRBConstr = model.AddConstr(x + y == 0, "c1")
- GRBConstr[] AddConstrs(int count)#
Add
count
new linear constraints to a model. The new constraints are all of the form0 <= 0
.We recommend that you build your model one constraint at a time (using
AddConstr
), since it introduces no significant overhead and we find that it produces simpler code. Feel free to use these methods if you disagree, though.- Parameters:
count – Number of constraints to add.
- Returns:
Array of new constraint objects.
- Example:
// Add 10 trivial linear constraints to model GRBConstr[] constrs = model.AddConstrs(10);
' Add 10 trivial linear constraints to model Dim constrs As GRBConstr() = model.AddConstrs(10)
- GRBConstr[] AddConstrs(GRBLinExpr[] lhsExprs, char[] senses, double[] rhsVals, string[] names)#
Add new linear constraints to a model. The number of added constraints is determined by the length of the input arrays (which must be consistent across all arguments).
We recommend that you build your model one constraint at a time (using
AddConstr
), since it introduces no significant overhead and we find that it produces simpler code. Feel free to use these methods if you disagree, though.- Parameters:
lhsExprs – Left-hand side expressions for the new linear constraints.
senses – Senses for new linear constraints (
GRB.LESS_EQUAL
,GRB.EQUAL
, orGRB.GREATER_EQUAL
).rhsVals – Right-hand side values for the new linear constraints.
names – Names for new constraints.
- Returns:
Array of new constraint objects.
- Example:
// Create variables GRBVar x = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "x"); GRBVar y = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y"); // Create linear expressions x + y and x - 2.0 * y GRBLinExpr lexpr1 = new GRBLinExpr(0); lexpr1.AddTerm(1.0, x); lexpr1.AddTerm(1.0, y); GRBLinExpr lexpr2 = new GRBLinExpr(0); lexpr2.AddTerm(1.0, x); lexpr2.AddTerm(-2.0, y); // Create arrays holding constraint data GRBLinExpr[] lexprs = {lexpr1, lexpr2}; char[] senses = {GRB.LESS_EQUAL, GRB.GREATER_EQUAL}; double[] rhsVals = {0.0, 1.0}; string[] names = {"c1", "c2"}; // Add constraints x + y <= 0.0 and x - 2.0 * y >= 1.0 GRBConstr[] constrs = model.AddConstrs(lexprs, senses, rhsVals, names);
' Create variables Dim x As GRBVar = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "x") Dim y As GRBVar = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y") ' Create linear expressions x + y and x - 2.0 * y Dim lexpr1 As GRBLinExpr = New GRBLinExpr(0) lexpr1.AddTerm(1.0, x) lexpr1.AddTerm(1.0, y) Dim lexpr2 As GRBLinExpr = New GRBLinExpr(0) lexpr2.AddTerm(1.0, x) lexpr2.AddTerm(-2.0, y) ' Create arrays holding constraint data Dim lexprs As GRBLinExpr() = New GRBLinExpr() {lexpr1, lexpr2} Dim senes As Char() = New Char() {GRB.LESS_EQUAL, GRB.GREATER_EQUAL} Dim rhsVals As Double() = New Double() {0.0, 1.0} Dim names As String() = New String() {"c1", "c2"} ' Add constraints x + y <= 0.0 and x - 2.0 * y >= 1.0 Dim constrs As GRBConstr() = model.AddConstrs(lexprs, senses, rhsVals, names)
- GRBConstr[] AddConstrs(GRBLinExpr[] lhsExprs, char[] senses, GRBLinExpr[] rhsExprs, int start, int len, string[] names)#
Add new linear constraints to a model. This signature allows you to use arrays to hold the various constraint attributes (left-hand side, sense, etc.), without forcing you to add one constraint for each entry in the array. The
start
andlen
arguments allow you to specify which constraints to add.We recommend that you build your model one constraint at a time (using
AddConstr
), since it introduces no significant overhead and we find that it produces simpler code. Feel free to use these methods if you disagree, though.- Parameters:
lhsExprs – Left-hand side expressions for the new linear constraints.
senses – Senses for new linear constraints (
GRB.LESS_EQUAL
,GRB.EQUAL
, orGRB.GREATER_EQUAL
).rhs – Right-hand side expressions for the new linear constraints.
start – The first constraint in the list to add.
len – The number of constraints to add.
names – Names for new constraints.
- Returns:
Array of new constraint objects.
- Example:
// Create variables GRBVar x = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "x"); GRBVar y = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y"); // Create linear expressions x + y and x - 2.0 * y GRBLinExpr lexpr1 = new GRBLinExpr(0); lexpr1.AddTerm(1.0, x); lexpr1.AddTerm(1.0, y); GRBLinExpr lexpr2 = new GRBLinExpr(0); lexpr2.AddTerm(1.0, x); lexpr2.AddTerm(-2.0, y); // Create arrays holding constraint data GRBLinExpr[] lexprs = {lexpr1, lexpr2}; char[] senses = {GRB.LESS_EQUAL, GRB.GREATER_EQUAL}; double[] rhsVals = {0.0, 1.0}; string[] names = {"c1", "c2"}; // Add constraints x + y <= 0.0 and x - 2.0 * y >= 1.0 model.AddConstrs(lexprs, senses, rhsVals, 0, 2, names);
' Create variables Dim x As GRBVar = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "x") Dim y As GRBVar = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y") ' Create linear expressions x + y and x - 2.0 * y Dim lexpr1 As GRBLinExpr = New GRBLinExpr(0) lexpr1.AddTerm(1.0, x) lexpr1.AddTerm(1.0, y) Dim lexpr2 As GRBLinExpr = New GRBLinExpr(0) lexpr2.AddTerm(1.0, x) lexpr2.AddTerm(-2.0, y) ' Create arrays holding constraint data Dim lexprs As GRBLinExpr() = New GRBLinExpr() {lexpr1, lexpr2} Dim senes As Char() = New Char() {GRB.LESS_EQUAL, GRB.GREATER_EQUAL} Dim rhsVals As Double() = New Double() {0.0, 1.0} Dim names As String() = New String() {"c1", "c2"} ' Add constraints x + y <= 0.0 and x - 2.0 * y >= 1.0 Dim constrs As GRBConstr() = model.AddConstrs(lexprs, senses, rhsVals, 0, 2 names)
- GRBGenConstr AddGenConstrMax(GRBVar resvar, GRBVar[] vars, double constant, string name)#
Add a new general constraint of type
GRB.GENCONSTR_MAX
to a model.A MAX constraint \(r = \max\{x_1,\ldots,x_n,c\}\) states that the resultant variable \(r\) should be equal to the maximum of the operand variables \(x_1,\ldots,x_n\) and the constant \(c\).
- Parameters:
resvar – The resultant variable of the new constraint.
vars – Array of variables that are the operands of the new constraint.
constant – The additional constant operand of the new constraint.
name – Name for the new general constraint.
- Returns:
New general constraint.
- Example:
// Create variables GRBVar resvar = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "resvar"); double[] ub = { 10.0, 10.0, 10.0 }; GRBVar[] x = model.AddVars(null, ub, null, null, null); // Add constraint resvar = max{x[0], x[1], x[2], 2.0} GRBGenConstr gc = model.AddGenConstrMax(resvar, x, 2.0, "maxconstr");
' Create variables Dim resvar As GRBVar = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "resvar") Dim ub As Double() = New Double() { 10.0, 10.0, 10.0 } Dim x As GRBVar() = model.AddVars(Nothing, ub, Nothing, Nothing, Nothing) ' Add constraint resvar = max{x[0], x[1], x[2], 2.0} Dim gc As GRBGenConstr = model.AddGenConstrMax(resvar, x, 2.0, "maxconstr")
- GRBGenConstr AddGenConstrMin(GRBVar resvar, GRBVar[] vars, double constant, string name)#
Add a new general constraint of type
GRB.GENCONSTR_MIN
to a model.A MIN constraint \(r = \min\{x_1,\ldots,x_n,c\}\) states that the resultant variable \(r\) should be equal to the minimum of the operand variables \(x_1,\ldots,x_n\) and the constant \(c\).
- Parameters:
resvar – The resultant variable of the new constraint.
vars – Array of variables that are the operands of the new constraint.
constant – The additional constant operand of the new constraint.
name – Name for the new general constraint.
- Returns:
New general constraint.
- Example:
// Create variables GRBVar resvar = model.AddVar(-GRB.INFINITY, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "resvar"); double[] lb = { -10.0, -10.0, -10.0 }; double[] ub = { 0.0, 0.0, 0.0 }; GRBVar[] x = model.AddVars(lb, ub, null, null, null); // Add constraint resvar = min{x[0], x[1], x[2], -2.0} GRBGenConstr gc = model.AddGenConstrMin(resvar, x, -2.0, "minconstr");
' Create variables Dim resvar As GRBVar = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "resvar") Dim lb As Double() = New Double() { -10.0, -10.0, -10.0 } Dim ub As Double() = New Double() { 0.0, 0.0, 0.0 } Dim x As GRBVar() = model.AddVars(lb, ub, Nothing, Nothing, Nothing) ' Add constraint resvar = min{x[0], x[1], x[2], -2.0} Dim gc As GRBGenConstr = model.AddGenConstrMin(resvar, x, -2.0, "minconstr")
- GRBGenConstr AddGenConstrAbs(GRBVar resvar, GRBVar argvar, string name)#
Add a new general constraint of type
GRB.GENCONSTR_ABS
to a model.An ABS constraint \(r = \mbox{abs}\{x\}\) states that the resultant variable \(r\) should be equal to the absolute value of the argument variable \(x\).
- Parameters:
resvar – The resultant variable of the new constraint.
argvar – The argument variable of the new constraint.
name – Name for the new general constraint.
- Returns:
New general constraint.
- Example:
// Create variables GRBVar resvar = model.AddVar(-GRB.INFINITY, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "resvar"); GRBVar x = model.AddVar(-2.0, 2.0, 0.0, GRB.CONTINUOUS, "x"); // Add constraint resvar = |x| GRBGenConstr gc = model.AddGenConstrAbs(resvar, x, "absconstr");
' Create variables Dim resvar As GRBVar = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "resvar") Dim x As GRBVar = model.AddVar(-2.0, 2.0, 0.0, GRB.CONTINUOUS, "x") ' Add constraint resvar = |x| Dim gc As GRBGenConstr = model.AddGenConstrAbs(resvar, x, "absconstr")
- GRBGenConstr AddGenConstrAnd(GRBVar resvar, GRBVar[] vars, string name)#
Add a new general constraint of type
GRB.GENCONSTR_AND
to a model.An AND constraint \(r = \mbox{and}\{x_1,\ldots,x_n\}\) states that the binary resultant variable \(r\) should be \(1\) if and only if all of the operand variables \(x_1,\ldots,x_n\) are equal to \(1\). If any of the operand variables is \(0\), then the resultant should be \(0\) as well.
Note that all variables participating in such a constraint will be forced to be binary, independent of how they were created.
- Parameters:
resvar – The resultant variable of the new constraint.
vars – Array of variables that are the operands of the new constraint.
name – Name for the new general constraint.
- Returns:
New general constraint.
- Example:
// Create binary variables GRBVar resvar = model.AddVar(0.0, 1.0, 0.0, GRB.BINARY, "resvar"); GRBVar[] x = model.AddVars(3, GRB.BINARY); // Add constraint resvar = AND{x[0], x[1], x[2]} GRBGenConstr gc = model.AddGenConstrAnd(resvar, x, "andconstr");
' Create variables Dim resvar As GRBVar = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "resvar") Dim x As GRBVar() = model.AddVars(3, GRB.BINARY) ' Add constraint resvar = AND{x[0], x[1], x[2]} Dim gc As GRBGenConstr = model.AddGenConstrAnd(resvar, x, "andconstr")
- GRBGenConstr AddGenConstrOr(GRBVar resvar, GRBVar[] vars, string name)#
Add a new general constraint of type
GRB.GENCONSTR_OR
to a model.An OR constraint \(r = \mbox{or}\{x_1,\ldots,x_n\}\) states that the binary resultant variable \(r\) should be \(1\) if and only if any of the operand variables \(x_1,\ldots,x_n\) is equal to \(1\). If all operand variables are \(0\), then the resultant should be \(0\) as well.
Note that all variables participating in such a constraint will be forced to be binary, independent of how they were created.
- Parameters:
resvar – The resultant variable of the new constraint.
vars – Array of variables that are the operands of the new constraint.
name – Name for the new general constraint.
- Returns:
New general constraint.
- Example:
// Create binary variables GRBVar resvar = model.AddVar(0.0, 1.0, 0.0, GRB.BINARY, "resvar"); GRBVar[] x = model.AddVars(3, GRB.BINARY); // Add constraint resvar = OR{x[0], x[1], x[2]} GRBGenConstr gc = model.AddGenConstrOr(resvar, x, "orconstr");
' Create variables Dim resvar As GRBVar = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "resvar") Dim x As GRBVar() = model.AddVars(3, GRB.BINARY) ' Add constraint resvar = OR{x[0], x[1], x[2]} Dim gc As GRBGenConstr = model.AddGenConstrOr(resvar, x, "orconstr")
- GRBGenConstr AddGenConstrNorm(GRBVar resvar, GRBVar[] vars, double which, string name)#
Add a new general constraint of type
GRB.GENCONSTR_NORM
to a model.A NORM constraint \(r = \mbox{norm}\{x_1,\ldots,x_n\}\) states that the resultant variable \(r\) should be equal to the vector norm of the argument vector \(x_1,\ldots,x_n\).
- Parameters:
resvar – The resultant variable of the new constraint.
vars – Array of variables that are the operands of the new constraint. Note that this array may not contain duplicates.
which – Which norm to use. Options are 0, 1, 2, and GRB.INFINITY.
name – Name for the new general constraint.
- Returns:
New general constraint.
- Example:
// Create variables GRBVar resvar = model.AddVar(-GRB.INFINITY, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "resvar"); double[] lb = { -10.0, -10.0, -10.0 }; double[] ub = { 10.0, 10.0, 10.0 }; GRBVar[] x = model.AddVars(lb, ub, null, null, null); // Add constraint resvar = (x_0^2 + x_1^2 + x_2^2)^(0.5) GRBGenConstr gc = model.AddGenConstrNorm(resvar, x, 2, "2normconstr");
' Create variables Dim resvar As GRBVar = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "resvar") Dim lb As Double() = New Double() { -10.0, -10.0, -10.0 } Dim ub As Double() = New Double() { 0.0, 0.0, 0.0 } Dim x As GRBVar() = model.AddVars(lb, ub, Nothing, Nothing, Nothing) ' Add constraint resvar = (x_0^2 + x_1^2 + x_2^2)^(0.5) Dim gc As GRBGenConstr = model.AddGenConstrNorm(resvar, x, 2, "2normconstr")
- GRBGenConstr AddGenConstrNL(GRBVar resvar, int[] opcode, double[] data, int[] parent, string name)#
Add a new general constraint of type
GRB.GENCONSTR_NL
to a model.A NL constraint \(r = f(x)\) states that the resultant variable \(r\) should be equal to the function value \(f(x)\) of the given function \(f\), provided as an expression tree described in Nonlinear Constraints.
- Parameters:
resvar – The resultant variable of the new constraint.
opcode – An array containing the operation codes for the nodes.
data – An array containing the auxiliary data for each node.
parent – An array providing the parent index of the nodes
name – Name for the new general constraint.
- Returns:
New general constraint.
- Example:
// Add nonlinear constraint x0 = sin(2.5 * x1) + x2 to the model GRBVar x0 = model.AddVar(0.0, 1.0, 0.0, GRB.CONTINUOUS, "x0"); GRBVar x1 = model.AddVar(0.0, 1.0, 0.0, GRB.CONTINUOUS, "x1"); GRBVar x2 = model.AddVar(0.0, 1.0, 0.0, GRB.CONTINUOUS, "x2"); // Initialize data for expression tree int[] opcode = new int[] {GRB.OPCODE_PLUS, GRB.OPCODE_SIN, GRB.OPCODE_MULTIPLY, GRB.OPCODE_CONSTANT, GRB.OPCODE_VARIABLE, GRB.OPCODE_VARIABLE}; double[] data = new double[] {-1.0, -1.0, -1.0, 2.5, 1.0, 2.0}; int[] parent = new int[] {-1, 0, 1, 2, 2, 0}; // Add nonlinear constraint model.AddGenConstrNL(x0, opcode, data, parent, "nlconstr");
' Add nonlinear constraint x0 = sin(2.5 * x1) + x2 to the model Dim x0 As GRBVar = model.AddVar(0.0, 1.0, 0.0, GRB.CONTINUOUS, "x0") Dim x1 As GRBVar = model.AddVar(0.0, 1.0, 0.0, GRB.CONTINUOUS, "x1") Dim x2 As GRBVar = model.AddVar(0.0, 1.0, 0.0, GRB.CONTINUOUS, "x2") ' Initialize data for expression tree Dim opcode As Integer() = New Integer() {GRB.OPCODE_PLUS, GRB.OPCODE_SIN, GRB.OPCODE_MULTIPLY, GRB.OPCODE_CONSTANT, GRB.OPCODE_VARIABLE, GRB.OPCODE_VARIABLE} Dim data As Double() = New Double() {-1.0, -1.0, -1.0, 2.5, 1.0, 2.0} Dim parent As Integer() = New Integer() {-1, 0, 1, 2, 2, 0} ' Add nonlinear constraint model.AddGenConstrNL(x0, opcode, data, parent, "nlconstr")
- GRBGenConstr AddGenConstrIndicator(GRBVar binvar, int binval, GRBLinExpr expr, char sense, double rhs, string name)#
Add a new general constraint of type
GRB.GENCONSTR_INDICATOR
to a model.An INDICATOR constraint \(z = f \rightarrow a^Tx \leq b\) states that if the binary indicator variable \(z\) is equal to \(f\), where \(f \in \{0,1\}\), then the linear constraint \(a^Tx \leq b\) should hold. On the other hand, if \(z = 1-f\), the linear constraint may be violated. The sense of the linear constraint can also be specified to be \(=\) or \(\geq\).
Note that the indicator variable \(z\) of a constraint will be forced to be binary, independent of how it was created.
- Parameters:
binvar – The binary indicator variable.
binval – The value for the binary indicator variable that would force the linear constraint to be satisfied (\(0\) or \(1\)).
expr – Left-hand side expression for the linear constraint triggered by the indicator.
sense – Sense for the linear constraint. Options are
GRB.LESS_EQUAL
,GRB.EQUAL
, orGRB.GREATER_EQUAL
.rhs – Right-hand side value for the linear constraint.
name – Name for the new general constraint.
- Returns:
New general constraint.
- Example:
// Create binary indicator variable GRBVar z = model.AddVar(0.0, 1.0, 0.0, GRB.BINARY, "z"); // Create variables GRBVar x = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "x"); GRBVar y = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y"); // Create linear expression x + y GRBLinExpr lexpr1 = new GRBLinExpr(0); lexpr1.AddTerm(1.0, x); lexpr1.AddTerm(1.0, y); // Add constraint if z = 1 then x + y <= 2 GRBGenConstr gc = model.AddGenConstrIndicator(z, 1, lexpr, GRB.LESS_EQUAL, 2.0, "indicatorconstr");
' Create binary indicator variable Dim z As GRBVar = model.AddVar(0.0, 1.0, 0.0, GRB.BINARY, "z") ' Create variables Dim x As GRBVar = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "x") Dim y As GRBVar = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y") ' Create linear expression x + y Dim lexpr1 As GRBLinExpr = New GRBLinExpr(0) lexpr1.AddTerm(1.0, x) lexpr1.AddTerm(1.0, y) ' Add constraint if z = 1 then x + y <= 2 Dim gc As GRBGenConstr = model.AddGenConstrIndicator(z, 1, lexpr, GRB.LESS_EQUAL, 2.0, "indicatorconstr")
- GRBGenConstr AddGenConstrIndicator(GRBVar binvar, int binval, GRBTempConstr constr, string name)#
Add a new general constraint of type
GRB.GENCONSTR_INDICATOR
to a model.An INDICATOR constraint \(z = f \rightarrow a^Tx \leq b\) states that if the binary indicator variable \(z\) is equal to \(f\), where \(f \in \{0,1\}\), then the linear constraint \(a^Tx \leq b\) should hold. On the other hand, if \(z = 1-f\), the linear constraint may be violated. The sense of the linear constraint can also be specified to be \(=\) or \(\geq\).
Note that the indicator variable \(z\) of a constraint will be forced to be binary, independent of how it was created.
- Parameters:
binvar – The binary indicator variable.
binval – The value for the binary indicator variable that would force the linear constraint to be satisfied (\(0\) or \(1\)).
constr – Temporary constraint object defining the linear constraint that is triggered by the indicator. The temporary constraint object is created using an overloaded comparison operator. See
GRBTempConstr
for more information.name – Name for the new general constraint.
- Returns:
New general constraint.
- Example:
// Create binary indicator variable GRBVar z = model.AddVar(0.0, 1.0, 0.0, GRB.BINARY, "z"); // Create variables GRBVar x = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "x"); GRBVar y = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y"); // Add constraint if z = 1 then x + y <= 2 GRBGenConstr gc = model.AddGenConstrIndicator(z, 1, x + y <= 2.0, "indicatorconstr");
' Create binary indicator variable Dim z As GRBVar = model.AddVar(0.0, 1.0, 0.0, GRB.BINARY, "z") ' Create variables Dim x As GRBVar = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "x") Dim y As GRBVar = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y") ' Add constraint if z = 1 then x + y <= 2 Dim gc As GRBGenConstr = model.AddGenConstrIndicator(z, 1, lexpr, GRB.LESS_EQUAL, 2.0, "indicatorconstr")
- GRBGenConstr AddGenConstrPWL(GRBVar xvar, GRBVar yvar, double[] xpts, double[] ypts, string name)#
Add a new general constraint of type
GRB.GENCONSTR_PWL
to a model.A piecewise-linear (PWL) constraint states that the relationship \(y = f(x)\) must hold between variables \(x\) and \(y\), where \(f\) is a piecewise-linear function. The breakpoints for \(f\) are provided as arguments. Refer to the description of piecewise-linear objectives for details of how piecewise-linear functions are defined.
- Parameters:
xvar – The \(x\) variable.
yvar – The \(y\) variable.
xpts – The \(x\) values for the points that define the piecewise-linear function. Must be in non-decreasing order.
ypts – The \(y\) values for the points that define the piecewise-linear function.
name – Name for the new general constraint.
- Returns:
New general constraint.
- Example:
// Create variables GRBVar x = model.AddVar(-1.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "x"); GRBVar y = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y"); // Create point pairs for the PWL function double[] xpts = {-1, 0, 0, 0, 1}; double[] ypts = {2, 1, 0, 1, 2}; // Add PWL constraint y = PWL(x) GRBGenConstr gc = model.AddGenConstrPWL(x, y, xpts, ypts, "pwlconstr");
' Create variables Dim x As GRBVar = model.AddVar(-1.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "x") Dim y As GRBVar = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y") ' Create point pairs for the PWL function Dim xpts As Double() = New Double() {-1, 0, 0, 0, 1} Dim ypts As Double() = New Double() {2, 1, 0, 1, 2} ' Add PWL constraint y = PWL(x) Dim gc As GRBGenConstr = model.AddGenConstrPWL(x, y, xpts, ypts, "pwlconstr")
- GRBGenConstr AddGenConstrPoly(GRBVar xvar, GRBVar yvar, double[] p, string name, string options)#
A polynomial function constraint states that the relationship \(y = p_0 x^d + p_1 x^{d-1} + ... + p_{d-1} x + p_{d}\) should hold between variables \(x\) and \(y\).
A piecewise-linear approximation of the function is added to the model. The details of the approximation are controlled using the following four attributes (or using the parameters with the same names): FuncPieces, FuncPieceError, FuncPieceLength, and FuncPieceRatio. Alternatively, the function can be treated as a nonlinear constraint by setting the attribute FuncNonlinear. For details, consult the General Constraint discussion.
- Parameters:
xvar – The \(x\) variable.
yvar – The \(y\) variable.
p – The coefficients for the polynomial function (starting with the coefficient for the highest power).
name – Name for the new general constraint.
options – A string that can be used to set the attributes that control the piecewise-linear approximation of this function constraint. To assign a value to an attribute, follow the attribute name with an equal sign and the desired value (with no spaces). Assignments for different attributes should be separated by spaces (e.g. “FuncPieces=-1 FuncPieceError=0.001”).
- Returns:
New general constraint.
- Example:
// Create argument variable GRBVar x = model.AddVar(-5.0, 5.0, 0.0, GRB.CONTINUOUS, "x"); // Create resultant variable GRBVar y = model.AddVar(-GRB.INFINITY, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y"); // Create array holding coefficients double[] p = {3.0, 2.0, 0.0, 1.0}; // Add constraint y = 3.0 * x^3 + 2.0 * x^2 + 1.0 GRBGenConstr gc = model.AddGenConstrPoly(x, y, p, "polyconstr", "");
' Create argument variable Dim x As GRBVar = model.AddVar(-5.0, 5.0, 0.0, GRB.CONTINUOUS, "x") ' Create resultant variable Dim y As GRBVar = model.AddVar(-GRB.INFINITY, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y") ' Create array holding coefficients Dim p As Double() = New Double() {3.0, 2.0, 0.0, 1.0} ' Add constraint y = 3.0 * x^3 + 2.0 * x^2 + 1.0 Dim gc As GRBGenConstr = model.AddGenConstrPoly(x, y, p, "polyconstr", "")
- GRBGenConstr AddGenConstrExp(GRBVar xvar, GRBVar yvar, string name, string options)#
Add a new general constraint of type
GRB.GENCONSTR_EXP
to a model.A natural exponential function constraint states that the relationship \(y = \exp(x)\) should hold for variables \(x\) and \(y\).
A piecewise-linear approximation of the function is added to the model. The details of the approximation are controlled using the following four attributes (or using the parameters with the same names): FuncPieces, FuncPieceError, FuncPieceLength, and FuncPieceRatio. Alternatively, the function can be treated as a nonlinear constraint by setting the attribute FuncNonlinear. For details, consult the General Constraint discussion.
- Parameters:
xvar – The \(x\) variable.
yvar – The \(y\) variable.
name – Name for the new general constraint.
options – A string that can be used to set the attributes that control the piecewise-linear approximation of this function constraint. To assign a value to an attribute, follow the attribute name with an equal sign and the desired value (with no spaces). Assignments for different attributes should be separated by spaces (e.g. “FuncPieces=-1 FuncPieceError=0.001”).
- Returns:
New general constraint.
- Example:
// Create argument variable GRBVar x = model.AddVar(-5.0, 5.0, 0.0, GRB.CONTINUOUS, "x"); // Create resultant variable GRBVar y = model.AddVar(-GRB.INFINITY, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y"); // Add constraint y = exp(x) GRBGenConstr gc = model.AddGenConstrExp(x, y, "expconstr", "");
' Create argument variable Dim x As GRBVar = model.AddVar(-5.0, 5.0, 0.0, GRB.CONTINUOUS, "x") ' Create resultant variable Dim y As GRBVar = model.AddVar(-GRB.INFINITY, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y") ' Add constraint y = exp(x) Dim gc As GRBGenConstr = model.AddGenConstrExp(x, y, "expconstr", "")
- GRBGenConstr AddGenConstrExpA(GRBVar xvar, GRBVar yvar, double a, string name, string options)#
Add a new general constraint of type
GRB.GENCONSTR_EXPA
to a model.An exponential function constraint states that the relationship \(y = a^x\) should hold for variables \(x\) and \(y\), where \(a > 0\) is the (constant) base.
A piecewise-linear approximation of the function is added to the model. The details of the approximation are controlled using the following four attributes (or using the parameters with the same names): FuncPieces, FuncPieceError, FuncPieceLength, and FuncPieceRatio. Alternatively, the function can be treated as a nonlinear constraint by setting the attribute FuncNonlinear. For details, consult the General Constraint discussion.
- Parameters:
xvar – The \(x\) variable.
yvar – The \(y\) variable.
a – The base of the function, \(a > 0\).
name – Name for the new general constraint.
options – A string that can be used to set the attributes that control the piecewise-linear approximation of this function constraint. To assign a value to an attribute, follow the attribute name with an equal sign and the desired value (with no spaces). Assignments for different attributes should be separated by spaces (e.g. “FuncPieces=-1 FuncPieceError=0.001”).
- Returns:
New general constraint.
- Example:
// Create argument variable GRBVar x = model.AddVar(1.0, 5.0, 0.0, GRB.CONTINUOUS, "x"); // Create resultant variable GRBVar y = model.AddVar(-GRB.INFINITY, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y"); // Add constraint y = 2.0^x GRBGenConstr gc = model.AddGenConstrExpA(x, y, 2.0, "exp2constr", "");
' Create argument variable Dim x As GRBVar = model.AddVar(1.0, 5.0, 0.0, GRB.CONTINUOUS, "x") ' Create resultant variable Dim y As GRBVar = model.AddVar(-GRB.INFINITY, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y") ' Add constraint y = 2.0^x Dim gc As GRBGenConstr = model.AddGenConstrExpA(x, y, 2.0, "exp2constr", "")
- GRBGenConstr AddGenConstrLog(GRBVar xvar, GRBVar yvar, string name, string options)#
Add a new general constraint of type
GRB.GENCONSTR_LOG
to a model.A natural logarithmic function constraint states that the relationship \(y = log(x)\) should hold for variables \(x\) and \(y\).
A piecewise-linear approximation of the function is added to the model. The details of the approximation are controlled using the following four attributes (or using the parameters with the same names): FuncPieces, FuncPieceError, FuncPieceLength, and FuncPieceRatio. Alternatively, the function can be treated as a nonlinear constraint by setting the attribute FuncNonlinear. For details, consult the General Constraint discussion.
- Parameters:
xvar – The \(x\) variable.
yvar – The \(y\) variable.
name – Name for the new general constraint.
options – A string that can be used to set the attributes that control the piecewise-linear approximation of this function constraint. To assign a value to an attribute, follow the attribute name with an equal sign and the desired value (with no spaces). Assignments for different attributes should be separated by spaces (e.g. “FuncPieces=-1 FuncPieceError=0.001”).
- Returns:
New general constraint.
- Example:
// Create argument variable GRBVar x = model.AddVar(1.0, 5.0, 0.0, GRB.CONTINUOUS, "x"); // Create resultant variable GRBVar y = model.AddVar(-GRB.INFINITY, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y"); // Add constraint y = log(x) GRBGenConstr gc = model.AddGenConstrLog(x, y, "logconstr", "");
' Create argument variable Dim x As GRBVar = model.AddVar(1.0, 5.0, 0.0, GRB.CONTINUOUS, "x") ' Create resultant variable Dim y As GRBVar = model.AddVar(-GRB.INFINITY, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y") ' Add constraint y = log(x) Dim gc As GRBGenConstr = model.AddGenConstrLog(x, y, "logconstr", "")
- GRBGenConstr AddGenConstrLogA(GRBVar xvar, GRBVar yvar, double a, string name, string options)#
Add a new general constraint of type
GRB.GENCONSTR_LOGA
to a model.A logarithmic function constraint states that the relationship \(y = log_a(x)\) should hold for variables \(x\) and \(y\), where \(a > 0\) is the (constant) base.
A piecewise-linear approximation of the function is added to the model. The details of the approximation are controlled using the following four attributes (or using the parameters with the same names): FuncPieces, FuncPieceError, FuncPieceLength, and FuncPieceRatio. Alternatively, the function can be treated as a nonlinear constraint by setting the attribute FuncNonlinear. For details, consult the General Constraint discussion.
- Parameters:
xvar – The \(x\) variable.
yvar – The \(y\) variable.
a – The base of the function, \(a > 0\).
name – Name for the new general constraint.
options – A string that can be used to set the attributes that control the piecewise-linear approximation of this function constraint. To assign a value to an attribute, follow the attribute name with an equal sign and the desired value (with no spaces). Assignments for different attributes should be separated by spaces (e.g. “FuncPieces=-1 FuncPieceError=0.001”).
- Returns:
New general constraint.
- Example:
// Create argument variable GRBVar x = model.AddVar(1.0, 5.0, 0.0, GRB.CONTINUOUS, "x"); // Create resultant variable GRBVar y = model.AddVar(-GRB.INFINITY, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y"); // Add constraint y = log_2(x) GRBGenConstr gc = model.AddGenConstrLogA(x, y, 2.0, "log2constr", "");
' Create argument variable Dim x As GRBVar = model.AddVar(1.0, 5.0, 0.0, GRB.CONTINUOUS, "x") ' Create resultant variable Dim y As GRBVar = model.AddVar(-GRB.INFINITY, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y") ' Add constraint y = log_2(x) Dim gc As GRBGenConstr = model.AddGenConstrLogA(x, y, 2.0, "log2constr", "")
- GRBGenConstr AddGenConstrLogistic(GRBVar xvar, GRBVar yvar, string name, string options)#
Add a new general constraint of type
GRB.GENCONSTR_LOGISTIC
to a model.A logistic function constraint states that the relationship \(y = \frac{1}{1 + e^{-x}}\) should hold for variables \(x\) and \(y\).
A piecewise-linear approximation of the function is added to the model. The details of the approximation are controlled using the following four attributes (or using the parameters with the same names): FuncPieces, FuncPieceError, FuncPieceLength, and FuncPieceRatio. Alternatively, the function can be treated as a nonlinear constraint by setting the attribute FuncNonlinear. For details, consult the General Constraint discussion.
- Parameters:
xvar – The \(x\) variable.
yvar – The \(y\) variable.
name – Name for the new general constraint.
options – A string that can be used to set the attributes that control the piecewise-linear approximation of this function constraint. To assign a value to an attribute, follow the attribute name with an equal sign and the desired value (with no spaces). Assignments for different attributes should be separated by spaces (e.g. “FuncPieces=-1 FuncPieceError=0.001”).
- Returns:
New general constraint.
- Example:
// Create argument variable GRBVar x = model.AddVar(-5.0, 5.0, 0.0, GRB.CONTINUOUS, "x"); // Create resultant variable GRBVar y = model.AddVar(-GRB.INFINITY, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y"); // Add constraint y = logistic(x) = 1.0 / (1.0 + exp(-x)) GRBGenConstr gc = model.AddGenConstrLogistic(x, y, "logisticconstr", "");
' Create argument variable Dim x As GRBVar = model.AddVar(-5.0, 5.0, 0.0, GRB.CONTINUOUS, "x") ' Create resultant variable Dim y As GRBVar = model.AddVar(-GRB.INFINITY, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y") ' Add constraint y = logistic(x) = 1.0 / (1.0 + exp(-x)) Dim gc As GRBGenConstr = model.AddGenConstrLogistic(x, y, "logisticconstr", "")
- GRBGenConstr AddGenConstrPow(GRBVar xvar, GRBVar yvar, double a, string name, string options)#
Add a new general constraint of type
GRB.GENCONSTR_POW
to a model.A power function constraint states that the relationship \(y = x^a\) should hold for variables \(x\) and \(y\), where \(a\) is the (constant) exponent.
If the exponent \(a\) is negative, the lower bound on \(x\) must be strictly positive. If the exponent isn’t an integer, the lower bound on \(x\) must be non-negative.
A piecewise-linear approximation of the function is added to the model. The details of the approximation are controlled using the following four attributes (or using the parameters with the same names): FuncPieces, FuncPieceError, FuncPieceLength, and FuncPieceRatio. Alternatively, the function can be treated as a nonlinear constraint by setting the attribute FuncNonlinear. For details, consult the General Constraint discussion.
- Parameters:
xvar – The \(x\) variable.
yvar – The \(y\) variable.
a – The exponent of the function.
name – Name for the new general constraint.
options – A string that can be used to set the attributes that control the piecewise-linear approximation of this function constraint. To assign a value to an attribute, follow the attribute name with an equal sign and the desired value (with no spaces). Assignments for different attributes should be separated by spaces (e.g. “FuncPieces=-1 FuncPieceError=0.001”).
- Returns:
New general constraint.
- Example:
// Create argument variable GRBVar x = model.AddVar(-5.0, 5.0, 0.0, GRB.CONTINUOUS, "x"); // Create resultant variable GRBVar y = model.AddVar(-GRB.INFINITY, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y"); // Add constraint y = x^3 GRBGenConstr gc = model.AddGenConstrPow(x, y, 3, "pow3constr", "");
' Create argument variable Dim x As GRBVar = model.AddVar(-5.0, 5.0, 0.0, GRB.CONTINUOUS, "x") ' Create resultant variable Dim y As GRBVar = model.AddVar(-GRB.INFINITY, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y") ' Add constraint y = x^3 Dim gc As GRBGenConstr = model.AddGenConstrPow(x, y, 3, "pow3constr", "")
- GRBGenConstr AddGenConstrSin(GRBVar xvar, GRBVar yvar, string name, string options)#
Add a new general constraint of type
GRB.GENCONSTR_SIN
to a model.A sine function constraint states that the relationship \(y = sin(x)\) should hold for variables \(x\) and \(y\).
A piecewise-linear approximation of the function is added to the model. The details of the approximation are controlled using the following four attributes (or using the parameters with the same names): FuncPieces, FuncPieceError, FuncPieceLength, and FuncPieceRatio. Alternatively, the function can be treated as a nonlinear constraint by setting the attribute FuncNonlinear. For details, consult the General Constraint discussion.
- Parameters:
xvar – The \(x\) variable.
yvar – The \(y\) variable.
name – Name for the new general constraint.
options – A string that can be used to set the attributes that control the piecewise-linear approximation of this function constraint. To assign a value to an attribute, follow the attribute name with an equal sign and the desired value (with no spaces). Assignments for different attributes should be separated by spaces (e.g. “FuncPieces=-1 FuncPieceError=0.001”).
- Returns:
New general constraint.
- Example:
// Create argument variable GRBVar x = model.AddVar(-5.0, 5.0, 0.0, GRB.CONTINUOUS, "x"); // Create resultant variable GRBVar y = model.AddVar(-GRB.INFINITY, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y"); // Add constraint y = sin(x) GRBGenConstr gc = model.AddGenConstrSin(x, y, "sinconstr", "");
' Create argument variable Dim x As GRBVar = model.AddVar(-5.0, 5.0, 0.0, GRB.CONTINUOUS, "x") ' Create resultant variable Dim y As GRBVar = model.AddVar(-GRB.INFINITY, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y") ' Add constraint y = sin(x) Dim gc As GRBGenConstr = model.AddGenConstrSin(x, y, "sinconstr", "")
- GRBGenConstr AddGenConstrCos(GRBVar xvar, GRBVar yvar, string name, string options)#
Add a new general constraint of type
GRB.GENCONSTR_COS
to a model.A cosine function constraint states that the relationship \(y = cos(x)\) should hold for variables \(x\) and \(y\).
A piecewise-linear approximation of the function is added to the model. The details of the approximation are controlled using the following four attributes (or using the parameters with the same names): FuncPieces, FuncPieceError, FuncPieceLength, and FuncPieceRatio. Alternatively, the function can be treated as a nonlinear constraint by setting the attribute FuncNonlinear. For details, consult the General Constraint discussion.
- Parameters:
xvar – The \(x\) variable.
yvar – The \(y\) variable.
name – Name for the new general constraint.
options – A string that can be used to set the attributes that control the piecewise-linear approximation of this function constraint. To assign a value to an attribute, follow the attribute name with an equal sign and the desired value (with no spaces). Assignments for different attributes should be separated by spaces (e.g. “FuncPieces=-1 FuncPieceError=0.001”).
- Returns:
New general constraint.
- Example:
// Create argument variable GRBVar x = model.AddVar(-5.0, 5.0, 0.0, GRB.CONTINUOUS, "x"); // Create resultant variable GRBVar y = model.AddVar(-GRB.INFINITY, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y"); // Add constraint y = cos(x) GRBGenConstr gc = model.AddGenConstrCos(x, y, "cosconstr", "");
' Create argument variable Dim x As GRBVar = model.AddVar(-5.0, 5.0, 0.0, GRB.CONTINUOUS, "x") ' Create resultant variable Dim y As GRBVar = model.AddVar(-GRB.INFINITY, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y") ' Add constraint y = cos(x) Dim gc As GRBGenConstr = model.AddGenConstrCos(x, y, "cosconstr", "")
- GRBGenConstr AddGenConstrTan(GRBVar xvar, GRBVar yvar, string name, string options)#
Add a new general constraint of type
GRB.GENCONSTR_TAN
to a model.A tangent function constraint states that the relationship \(y = tan(x)\) should hold for variables \(x\) and \(y\).
A piecewise-linear approximation of the function is added to the model. The details of the approximation are controlled using the following four attributes (or using the parameters with the same names): FuncPieces, FuncPieceError, FuncPieceLength, and FuncPieceRatio. Alternatively, the function can be treated as a nonlinear constraint by setting the attribute FuncNonlinear. For details, consult the General Constraint discussion.
- Parameters:
xvar – The \(x\) variable.
yvar – The \(y\) variable.
name – Name for the new general constraint.
options – A string that can be used to set the attributes that control the piecewise-linear approximation of this function constraint. To assign a value to an attribute, follow the attribute name with an equal sign and the desired value (with no spaces). Assignments for different attributes should be separated by spaces (e.g. “FuncPieces=-1 FuncPieceError=0.001”).
- Returns:
New general constraint.
- Example:
// Create argument variable GRBVar x = model.AddVar(-1.0, 1.0, 0.0, GRB.CONTINUOUS, "x"); // Create resultant variable GRBVar y = model.AddVar(-GRB.INFINITY, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y"); // Add constraint y = tan(x) GRBGenConstr gc = model.AddGenConstrTan(x, y, "tanconstr", "");
' Create argument variable Dim x As GRBVar = model.AddVar(-5.0, 5.0, 0.0, GRB.CONTINUOUS, "x") ' Create resultant variable Dim y As GRBVar = model.AddVar(-GRB.INFINITY, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y") ' Add constraint y = tan(x) Dim gc As GRBGenConstr = model.AddGenConstrTan(x, y, "tanconstr", "")
- GRBQConstr AddQConstr(GRBQuadExpr lhsExpr, char sense, GRBQuadExpr rhsExpr, string name)#
Add a quadratic constraint to a model.
Important
Gurobi can handle both convex and non-convex quadratic constraints. The differences between them can be both important and subtle. Refer to this discussion for additional information.
- Parameters:
lhsExpr – Left-hand side expression for new quadratic constraint.
sense – Sense for new quadratic constraint (
GRB.LESS_EQUAL
,GRB.EQUAL
, orGRB.GREATER_EQUAL
).rhsExpr – Right-hand side expression for new quadratic constraint.
name – Name for new constraint.
- Returns:
New quadratic constraint object.
- Example:
// Create variables GRBVar x = model.AddVar(-2.0, 2.0, 0.0, GRB.CONTINUOUS, "x"); GRBVar y = model.AddVar(0.0, 3.0, 0.0, GRB.CONTINUOUS, "y"); // Create quadratric expression x^2 + x*y + y GRBQuadExpr qexpr = new GRBQuadExpr(0); qexpr.AddTerm(1.0, x, x); qexpr.AddTerm(1.0, x, y); qexpr.AddTerm(1.0, y); // Add quadratic constraint x^2 + x*y + y = 0 with name c1 GRBQConstr constr = model.AddQConstr(qexpr, GRB.EQUAL, 0.0, "c1");
' Create variables Dim x As GRBVar = model.AddVar(-2.0, 2.0, 0.0, GRB.CONTINUOUS, "x") Dim y As GRBVar = model.AddVar(0.0, 3.0, 0.0, GRB.CONTINUOUS, "y") ' Create quadratric expression x^2 + x*y + y Dim qexpr As GRBQuadExpr = New GRBQuadExpr(0) qexpr.AddTerm(1.0, x, x) qexpr.AddTerm(1.0, x, y) qexpr.AddTerm(1.0, y) ' Add quadratic constraint x^2 + x*y + y = 0 with name c1 Dim constr As GRBQConstr = model.AddQConstr(qexpr, GRB.EQUAL, 0.0, "c1")
- GRBQConstr AddQConstr(GRBTempConstr tempConstr, string name)#
Add a quadratic constraint to a model.
Important
Gurobi can handle both convex and non-convex quadratic constraints. The differences between them can be both important and subtle. Refer to this discussion for additional information.
- Parameters:
tempConstr – Temporary constraint object, created by an overloaded comparison operator. See
GRBTempConstr
for more information.name – Name for new constraint.
- Returns:
New quadratic constraint object.
- Example:
// Create variables GRBVar x = model.AddVar(-2.0, 2.0, 0.0, GRB.CONTINUOUS, "x"); GRBVar y = model.AddVar(0.0, 3.0, 0.0, GRB.CONTINUOUS, "y"); // Add quadratic constraint x^2 + x*y + y = 0 with name c1 GRBQConstr constr = model.AddQConstr(x*x + x*y + y == 0, "c1");
' Create variables Dim x As GRBVar = model.AddVar(-2.0, 2.0, 0.0, GRB.CONTINUOUS, "x") Dim y As GRBVar = model.AddVar(0.0, 3.0, 0.0, GRB.CONTINUOUS, "y") ' Add quadratic constraint x^2 + x*y + y = 0 with name c1 Dim constr As GRBQConstr = model.AddQConstr(x*x + x*y + y == 0, "c1")
- GRBConstr AddRange(GRBLinExpr expr, double lower, double upper, string name)#
Add a single range constraint to a model. A range constraint states that the value of the input expression must be between the specified
lower
andupper
bounds in any solution.Note that range constraints are stored internally as equality constraints. We add an extra variable to the model to capture the range information. Thus, the Sense attribute on a range constraint will always be
GRB.EQUAL
. In particular introducing a range constraint\[L \leq a^T x \leq U\]is equivalent to adding a slack variable \(s\) and the following constraints
\[\begin{split}\begin{array}{rl} a^T x - s & = L \\ 0 \leq s & \leq U - L. \end{array}\end{split}\]- Parameters:
expr – Linear expression for new range constraint.
lower – Lower bound for linear expression.
upper – Upper bound for linear expression.
name – Name for new constraint.
- Returns:
New constraint object.
- Example:
// Create variables GRBVar x = model.AddVar(0.0, 10.0, 0.0, GRB.CONTINUOUS, "x"); GRBVar y = model.AddVar(-10.0, 3.0, 0.0, GRB.CONTINUOUS, "y"); // Create linear expression x + y GRBLinExpr lexpr = new GRBLinExpr(0); lexpr.AddTerm(1.0, x); lexpr.AddTerm(1.0, y); // Add range constraints -3 <= x + y <= 2 with name c1 GRBConstr constr = model.AddRange(lexpr, -3.0, 2.0, "c1");
' Create variables Dim x As GRBVar = model.AddVar(0.0, 10.0, 0.0, GRB.CONTINUOUS, "x") Dim y As GRBVar = model.AddVar(-10.0, 3.0, 0.0, GRB.CONTINUOUS, "y") ' Create linear expression x + y Dim lexpr As GRBLinExpr = new GRBLinExpr(0) lexpr.AddTerm(1.0, x) lexpr.AddTerm(1.0, y) ' Add range constraints -3 <= x + y <= 2 with name c1 Dim constr As GRBConstr = model.AddRange(lexpr, -3.0, 2.0, "c1")
- GRBConstr[] AddRanges(GRBLinExpr[] exprs, double[] lower, double[] upper, string[] names)#
Add new range constraints to a model. A range constraint states that the value of the input expression must be between the specified
lower
andupper
bounds in any solution.- Parameters:
exprs – Linear expressions for the new range constraints.
lower – Lower bounds for linear expressions.
upper – Upper bounds for linear expressions.
name – Names for new range constraints.
count – Number of range constraints to add.
- Returns:
Array of new constraint objects.
- Example:
// Create variables GRBVar x = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "x"); GRBVar y = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y"); // Create linear expressions x + y and x - 2.0 * y GRBLinExpr lexpr1 = new GRBLinExpr(0); lexpr1.AddTerm(1.0, x); lexpr1.AddTerm(1.0, y); GRBLinExpr lexpr2 = new GRBLinExpr(0); lexpr2.AddTerm(1.0, x); lexpr2.AddTerm(-2.0, y); double[] lower = {-3.0, 2.0}; double[] upper = {-1.0, 5.0}; string[] names = {"c1", "c2"}; // Add constraints -3.0 <= x + y <= 2.0 and -1.0 <= x - 2.0 * y <= 5.0 GRBConstr[] constrs = model.AddRanges(lexprs, lower, upper, names);
' Create variables Dim x As GRBVar = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "x") Dim y As GRBVar = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y") ' Create linear expressions x + y and x - 2.0 * y Dim lexpr1 As GRBLinExpr = New GRBLinExpr(0) lexpr1.AddTerm(1.0, x) lexpr1.AddTerm(1.0, y) Dim lexpr2 As GRBLinExpr = New GRBLinExpr(0) lexpr2.AddTerm(1.0, x) lexpr2.AddTerm(-2.0, y) Dim lower As Double() = New Double() {-3.0, 2.0} Dim upper As Double() = New Double() {-1.0, 5.0} Dim names As String() = New String() {"c1", "c2"} ' Add constraints -3.0 <= x + y <= 2.0 and -1.0 <= x - 2.0 * y <= 5.0 Dim constrs As GRBConstr() = model.AddRanges(lexprs, lower, upper, names)
- GRBSOS AddSOS(GRBVar[] vars, double[] weights, int type)#
Add an SOS constraint to the model. Please refer to this section for details on SOS constraints.
- Parameters:
vars – Array of variables that participate in the SOS constraint.
weights – Weights for the variables in the SOS constraint.
type – SOS type (can be
GRB.SOS_TYPE1
orGRB.SOS_TYPE2
).
- Returns:
New SOS constraint.
- Example:
// Create variables GRBVar x = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "x"); GRBVar y = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y"); // Create helper arrays GRBVar[] vars = {x, y}; double[] weights = {1.0, 2.0}; // Add SOS1 constraint over x and y GRBSOS constr = model.AddSOS(vars, weights, GRB.SOS_TYPE1);
' Create variables Dim x As GRBVar = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "x") Dim y As GRBVar = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y") ' Create helper arrays Dim vars As GRBVar() = New GRBVar() {x, y} Dim weights As Double() = New Double() {1.0, 2.0} ' Add SOS1 constraint over x and y Dim constr As GRBSOS = model.AddSOS(vars, weights, GRB.SOS_TYPE1)
- GRBVar AddVar(double lb, double ub, double obj, char type, string name)#
Add a single decision variable to a model; non-zero entries will be added later.
- Parameters:
lb – Lower bound for new variable.
ub – Upper bound for new variable.
obj – Objective coefficient for new variable.
type – Variable type for new variable (
GRB.CONTINUOUS
,GRB.BINARY
,GRB.INTEGER
,GRB.SEMICONT
, orGRB.SEMIINT
).name – Name for new variable.
- Returns:
New variable object.
- Example:
// Create variable GRBVar x = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "x");
' Create variable Dim x As GRBVar = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "x")
- GRBVar AddVar(double lb, double ub, double obj, char type, GRBConstr[] constrs, double[] coeffs, string name)#
Add a single decision variable and the associated non-zero coefficients to a model.
- Parameters:
lb – Lower bound for new variable.
ub – Upper bound for new variable.
obj – Objective coefficient for new variable.
type – Variable type for new variable (
GRB.CONTINUOUS
,GRB.BINARY
,GRB.INTEGER
,GRB.SEMICONT
, orGRB.SEMIINT
).constrs – Array of constraints in which the variable participates.
coeffs – Array of coefficients for each constraint in which the variable participates. The lengths of the
constrs
andcoeffs
arrays must be identical.name – Name for new variable.
- Returns:
New variable object.
- Example:
// Add 3 trivial linear constraints to model GRBConstr[] constrs = model.AddConstrs(3); // Constraint coefficients for variable x double[] coeffs = {1.0, 2.0, 3.0}; // Add variable x with coeffs 1.0, 2.0, 3.0 to the newly created trivial constraints GRBVar x = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, constrs, coeffs, "x");
' Add 3 trivial linear constraints to model Dim constrs As GRBConstr() = model.AddConstrs(3) ' Constraint coefficients for variable x Dim coeffs As Double() = New Double() {1.0, 2.0, 3.0} ' Add variable x with coeffs 1.0, 2.0, 3.0 to the newly created trivial constraints Dim x As GRBVar = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, constrs, coeffs, "x")
- GRBVar AddVar(double lb, double ub, double obj, char type, GRBColumn col, string name)#
Add a variable to a model. This signature allows you to specify the set of constraints to which the new variable belongs using a
GRBColumn
object.- Parameters:
lb – Lower bound for new variable.
ub – Upper bound for new variable.
obj – Objective coefficient for new variable.
type – Variable type for new variable (
GRB.CONTINUOUS
,GRB.BINARY
,GRB.INTEGER
,GRB.SEMICONT
, orGRB.SEMIINT
).col – GRBColumn object for specifying a set of constraints to which new variable belongs.
name – Name for new variable.
- Returns:
New variable object.
- Example:
// Add 3 trivial linear constraints to model GRBConstr[] constrs = model.AddConstrs(3); // Constraint coefficients for variable x double[] coeffs = {1.0, 2.0, 3.0}; // Create and fill GRBColumn object GRBColumn col = new GRBColumn(); col.AddTerms(coeffs, constrs); // Add variable x with coefs 1.0, 2.0, 3.0 to the newly created trivial constraints GRBVar x = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, col, "x");
' Add 3 trivial linear constraints to model Dim constrs As GRBConstr() = model.AddConstrs(3) ' Constraint coefficients for variable x Dim coeffs As Double() = {1.0, 2.0, 3.0} ' Create and fill GRBColumn object Dim col As GRBColumn = New GRBColumn() col.AddTerms(coeffs, constrs) ' Add variable x with coefs 1.0, 2.0, 3.0 to the newly created trivial constraints Dim x As GRBVar = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, col, "x")
- GRBVar[] AddVars(int count, char type)#
Add
count
new decision variables to a model. All associated attributes take their default values, except the variabletype
, which is specified as an argument.- Parameters:
count – Number of variables to add.
type – Variable type for new variables (
GRB.CONTINUOUS
,GRB.BINARY
,GRB.INTEGER
,GRB.SEMICONT
, orGRB.SEMIINT
).
- Returns:
Array of new variable objects.
- Example:
// Add 3 binary variables GRBVar[] x = model.AddVars(3, GRB.BINARY);
' Add 3 binary variables Dim x As GRBVar() = model.AddVars(3, GRB.BINARY)
- GRBVar[] AddVars(double[] lb, double[] ub, double[] obj, char[] type, string[] names)#
Add new decision variables to a model. The number of added variables is determined by the length of the input arrays (which must be consistent across all arguments).
- Parameters:
lb – Lower bounds for new variables. Can be
null
, in which case the variables get lower bounds of 0.0.ub – Upper bounds for new variables. Can be
null
, in which case the variables get infinite upper bounds.obj – Objective coefficients for new variables. Can be
null
, in which case the variables get objective coefficients of 0.0.type – Variable types for new variables (
GRB.CONTINUOUS
,GRB.BINARY
,GRB.INTEGER
,GRB.SEMICONT
, orGRB.SEMIINT
). Can benull
, in which case the variables are assumed to be continuous.names – Names for new variables. Can be
null
, in which case all variables are given default names.
- Returns:
Array of new variable objects.
- Example:
// Create 3 variables with default lower bound and default type double[] ub = {1, 1, 2}; double[] obj = {-2, -1, -1}; string[] names = {"x0", "x1", "x2"}; GRBVar[] x = model.AddVars(null, ub, obj, null, names);
' Create 3 variables with default lower bound and default type Dim ub As Double() = New Double() {1, 1, 2} Dim obj As Double() = New Double() {-2, -1, -1} Dim names As String() = New String() {"x0", "x1", "x2"} Dim x As GRBVar() = model.AddVars(Nothing, ub, obj, Nothing, names)
- GRBVar[] AddVars(double[] lb, double[] ub, double[] obj, char[] type, string[] names, int start, int len)#
Add new decision variables to a model. This signature allows you to use arrays to hold the various variable attributes (lower bound, upper bound, etc.), without forcing you to add a variable for each entry in the array. The
start
andlen
arguments allow you to specify which variables to add.- Parameters:
lb – Lower bounds for new variables. Can be
null
, in which case the variables get lower bounds of 0.0.ub – Upper bounds for new variables. Can be
null
, in which case the variables get infinite upper bounds.obj – Objective coefficients for new variables. Can be
null
, in which case the variables get objective coefficients of 0.0.type – Variable types for new variables (
GRB.CONTINUOUS
,GRB.BINARY
,GRB.INTEGER
,GRB.SEMICONT
, orGRB.SEMIINT
). Can benull
, in which case the variables are assumed to be continuous.names – Names for new variables. Can be
null
, in which case all variables are given default names.start – The first variable in the list to add.
len – The number of variables to add.
- Returns:
Array of new variable objects.
- Example:
// Create 2 variables with default lower bound and default type double[] ub = {1, 1, 2}; double[] obj = {-2, -1, -1}; string[] names = {"x0", "x1", "x2"}; GRBVar[] x = model.AddVars(null, ub, obj, null, names, 0, 2);
' Create 3 variables with default lower bound and default type Dim ub As Double() = New Double() {1, 1, 2} Dim obj As Double() = New Double() {-2, -1, -1} Dim names As String() = New String() {"x0", "x1", "x2"} Dim x As GRBVar() = model.AddVars(Nothing, ub, obj, Nothing, names, 0, 3)
- GRBVar[] AddVars(double[] lb, double[] ub, double[] obj, char[] type, string[] names, GRBColumn[] col)#
Add new decision variables to a model. This signature allows you to specify the list of constraints to which each new variable belongs using an array of
GRBColumn
objects.- Parameters:
lb – Lower bounds for new variables. Can be
null
, in which case the variables get lower bounds of 0.0.ub – Upper bounds for new variables. Can be
null
, in which case the variables get infinite upper bounds.obj – Objective coefficients for new variables. Can be
null
, in which case the variables get objective coefficients of 0.0.type – Variable types for new variables (
GRB.CONTINUOUS
,GRB.BINARY
,GRB.INTEGER
,GRB.SEMICONT
, orGRB.SEMIINT
). Can benull
, in which case the variables are assumed to be continuous.names – Names for new variables. Can be
null
, in which case all variables are given default names.cols – GRBColumn objects for specifying a set of constraints to which each new column belongs.
- Returns:
Array of new variable objects.
- Example:
// Create 3 variables with default lower bound and default type double[] ub = {1, 1, 2}; double[] obj = {-2, -1, -1}; string[] names = {"x0", "x1", "x2"}; // Create an array of previously created GRBColumn objects GRBColumn[] col = {col1, col2, col3}; GRBVar[] x = model.AddVars(null, ub, obj, null, names, col);
' Create 3 variables with default lower bound and default type Dim ub As Double() = New Double() {1, 1, 2} Dim obj As Double() = New Double() {-2, -1, -1} Dim names As String() = New String() {"x0", "x1", "x2"} ' Create an array of previously created GRBColumn objects Dim cols As GRBColumn() = New GRBColumn() {col1, col2, col3} Dim x As GRBVar() = model.AddVars(Nothing, ub, obj, Nothing, names, col)
- void ChgCoeff(GRBConstr constr, GRBVar var, double newvalue)#
Change one coefficient in the model. The desired change is captured using a
GRBVar
object, aGRBConstr
object, and a desired coefficient for the specified variable in the specified constraint. If you make multiple changes to the same coefficient, the last one will be applied.Note that, due to our lazy update approach, the change won’t actually take effect until you update the model (using
GRBModel.Update
), optimize the model (usingGRBModel.Optimize
), or write the model to disk (usingGRBModel.Write
).- Parameters:
constr – Constraint for coefficient to be changed.
var – Variable for coefficient to be changed.
newvalue – Desired new value for coefficient.
- Example:
// Change coefficient of variable x in constraint c1 to 2.0 model.ChgCoeff(c1, x, 2.0);
' Change coefficient of variable x in constraint c1 to 2.0 model.ChgCoeff(c1, x, 2.0)
- void ChgCoeffs(GRBConstr[] constrs, GRBVar[] vars, double[] vals)#
Change a list of coefficients in the model. Each desired change is captured using a
GRBVar
object, aGRBConstr
object, and a desired coefficient for the specified variable in the specified constraint. The entries in the input arrays each correspond to a single desired coefficient change. The lengths of the input arrays must all be the same. If you make multiple changes to the same coefficient, the last one will be applied.Note that, due to our lazy update approach, the change won’t actually take effect until you update the model (using
GRBModel.Update
), optimize the model (usingGRBModel.Optimize
), or write the model to disk (usingGRBModel.Write
).- Parameters:
constrs – Constraints for coefficients to be changed.
vars – Variables for coefficients to be changed.
vals – Desired new values for coefficients.
- Example:
// Create arrays using previously created constraints and variables GRBConstr[] constrs = {c1, c2, c3}; GRBVar[] vars = {x, y, z}; double[] vals = {1.0, 2.0, 3.0}; // Change coefficients of variables x, y, z in constraints c1, c2, and c3, respectively model.ChgCoeffs(constrs, vars, vals);
' Create arrays using previously created constraints and variables Dim constrs As GRBConstr() = New GRBConstr() {c1, c2, c3} Dim vars As GRBVar() = New GRBVar() {x, y, z} Dim vals As Double() = New Double() {1.0, 2.0, 3.0} ' Change coefficients of variables x, y, z in constraints c1, c2, and c3, respectively model.ChgCoeffs(constrs, vars, vals)
- void ComputeIIS()#
Compute an Irreducible Inconsistent Subsystem (IIS).
An IIS is a subset of the constraints and variable bounds with the following properties:
It is still infeasible, and
If a single constraint or bound is removed, the subsystem becomes feasible.
Note that an infeasible model may have multiple IISs. The one returned by Gurobi is not necessarily the smallest one; there may exist others with fewer constraints or bounds.
IIS results are returned in a number of attributes: IISConstr, IISLB, IISUB, IISSOS, IISQConstr, and IISGenConstr. Each indicates whether the corresponding model element is a member of the computed IIS.
Note that for models with general function constraints, piecewise-linear approximation of the constraints may cause unreliable IIS results.
The IIS log provides information about the progress of the algorithm, including a guess at the eventual IIS size.
If an IIS computation is interrupted before completion, Gurobi will return the smallest infeasible subsystem found to that point.
The IISConstrForce, IISLBForce, IISUBForce, IISSOSForce, IISQConstrForce, and IISGenConstrForce attributes allow you mark model elements to either include or exclude from the computed IIS. Setting the attribute to 1 forces the corresponding element into the IIS, setting it to 0 forces it out of the IIS, and setting it to -1 allows the algorithm to decide.
To give an example of when these attributes might be useful, consider the case where an initial model is known to be feasible, but it becomes infeasible after adding constraints or tightening bounds. If you are only interested in knowing which of the changes caused the infeasibility, you can force the unmodified bounds and constraints into the IIS. That allows the IIS algorithm to focus exclusively on the new constraints, which will often be substantially faster.
Note that setting any of the
Force
attributes to 0 may make the resulting subsystem feasible, which would then make it impossible to construct an IIS. Trying anyway will result in a IIS_NOT_INFEASIBLE error. Similarly, setting this attribute to 1 may result in an IIS that is not irreducible. More precisely, the system would only be irreducible with respect to the model elements that have force values of -1 or 0.This method populates the IISConstr, IISQConstr, and IISGenConstr constraint attributes, the IISSOS, SOS attribute, and the IISLB and IISUB variable attributes. You can also obtain information about the results of the IIS computation by writing a
.ilp
format file (seeGRBModel.Write
). This file contains only the IIS from the original model.Use the IISMethod parameter to adjust the behavior of the IIS algorithm.
Note that this method can be used to compute IISs for both continuous and MIP models.
- Example:
// Compute IIS for infeasible model if (model.Status == GRB.Status.INFEASIBLE) { model.ComputeIIS(); }
' Compute IIS for infeasible model If (model.Status = GRB.Status.INFEASIBLE) Then model.ComputeIIS() End If
- void DiscardConcurrentEnvs()#
Discard concurrent environments for a model.
The concurrent environments created by
GetConcurrentEnv
will be used by every subsequent call to the concurrent optimizer until the concurrent environments are discarded.- Example:
env0 = model.GetConcurrentEnv(0); env1 = model.GetConcurrentEnv(1); env0.Set(GRB.IntParam.Method, 0); env1.Set(GRB.IntParam.Method, 1); model.Optimize(); model.DiscardConcurrentEnvs();
env0 = model.GetConcurrentEnv(0) env1 = model.GetConcurrentEnv(1) env0.Set(GRB.IntParam.Method, 0) env1.Set(GRB.IntParam.Method, 1) model.Optimize() model.DiscardConcurrentEnvs()
- void DiscardMultiobjEnvs()#
Discard all multi-objective environments associated with the model, thus restoring multi objective optimization to its default behavior.
Please refer to the discussion of Multiple Objectives for information on how to specify multiple objective functions and control the trade-off between them.
Use
GetMultiobjEnv
to create a multi-objective environment.- Example:
env0 = model.GetMultiobjEnv(0); env1 = model.GetMultiobjEnv(1); env0.Set(GRB.IntParam.Method, 0); env1.Set(GRB.IntParam.Method, 1); model.Optimize(); model.DiscardMultiobjEnvs();
env0 = model.GetMultiobjEnv(0) env1 = model.GetMultiobjEnv(1) env0.Set(GRB.IntParam.Method, 0) env1.Set(GRB.IntParam.Method, 1) model.Optimize() model.DiscardMultiobjEnvs()
- void Dispose()#
Release the resources associated with a
GRBModel
object. While the .NET garbage collector will eventually reclaim these resources, we recommend that you call theDispose
method when you are done using a model.You should not attempt to use a
GRBModel
object after callingDispose
on it.- Example:
GRBEnv env = new GRBEnv(); GRBModel model = new GRBModel(env); // ... model.Optimize(); model.Dispose(); env.Dispose();
Dim env As GRBEnv = New GRBEnv() Dim model As GRBModel = New GRBModel(env) ' ... model.Optimize() model.Dispose() env.Dispose()
- double FeasRelax(int relaxobjtype, boolean minrelax, GRBVar[] vars, double[] lbpen, double[] ubpen, GRBConstr[] constrs, double[] rhspen)#
Modifies the
GRBModel
object to create a feasibility relaxation. Note that you need to callOptimize
on the result to compute the actual relaxed solution.The feasibility relaxation is a model that, when solved, minimizes the amount by which the solution violates the bounds and linear constraints of the original model. This method provides a number of options for specifying the relaxation.
If you specify
relaxobjtype=0
, the objective of the feasibility relaxation is to minimize the sum of the weighted magnitudes of the bound and constraint violations. Thelbpen
,ubpen
, andrhspen
arguments specify the cost per unit violation in the lower bounds, upper bounds, and linear constraints, respectively.If you specify
relaxobjtype=1
, the objective of the feasibility relaxation is to minimize the weighted sum of the squares of the bound and constraint violations. Thelbpen
,ubpen
, andrhspen
arguments specify the coefficients on the squares of the lower bound, upper bound, and linear constraint violations, respectively.If you specify
relaxobjtype=2
, the objective of the feasibility relaxation is to minimize the weighted count of bound and constraint violations. Thelbpen
,ubpen
, andrhspen
arguments specify the cost of violating a lower bound, upper bound, and linear constraint, respectively.To give an example, if a constraint with
rhspen
valuep
is violated by 2.0, it would contribute2*p
to the feasibility relaxation objective forrelaxobjtype=0
, it would contribute2*2*p
forrelaxobjtype=1
, and it would contributep
forrelaxobjtype=2
.The
minrelax
argument is a boolean that controls the type of feasibility relaxation that is created. Ifminrelax=false
, optimizing the returned model gives a solution that minimizes the cost of the violation. Ifminrelax=true
, optimizing the returned model finds a solution that minimizes the original objective, but only from among those solutions that minimize the cost of the violation. Note thatfeasRelax
must solve an optimization problem to find the minimum possible relaxation whenminrelax=true
, which can be quite expensive.There are two signatures for this method. The more complex one takes a list of variables and constraints, as well as penalties associated with relaxing the corresponding lower bounds, upper bounds, and constraints. If a variable or constraint is not included in one of these lists, the associated bounds or constraints may not be violated. The simpler signature takes a pair of boolean arguments,
vrelax
andcrelax
, that indicate whether variable bounds and/or constraints can be violated. Ifvrelax
/crelax
istrue
, then every bound/constraint is allowed to be violated, respectively, and the associated cost is 1.0.For an example of how this routine transforms a model, and more details about the variables and constraints created, please see this section.
Note that this is a destructive method: it modifies the model on which it is invoked. If you don’t want to modify your original model, use the
GRBModel constructor
to create a copy before invoking this method.Create a feasibility relaxation model.
- Parameters:
relaxobjtype – The cost function used when finding the minimum cost relaxation.
minrelax – The type of feasibility relaxation to perform.
vars – Variables whose bounds are allowed to be violated.
lbpen – Penalty for violating a variable lower bound. One entry for each variable in argument
vars
.ubpen – Penalty for violating a variable upper bound. One entry for each variable in argument
vars
.constrs – Linear constraints that are allowed to be violated.
rhspen – Penalty for violating a linear constraint. One entry for each constraint in argument
constrs
.
- Returns:
Zero if
minrelax
is false. Ifminrelax
is true, the return value is the objective value for the relaxation performed. If the value is less than 0, it indicates that the method failed to create the feasibility relaxation.- Example:
// Compute feasibility relaxation for infeasible model if (model.Status == GRB.Status.INFEASIBLE) { GRBVar[] vars = model.GetVars(); double[] ubpen = new double[model.NumVars]; for (int i = 0; i < model.NumVars; i++) { ubpen[i] = 1.0; } model.FeasRelax(0, false, vars, null, ubpen, null, null); model.Optimize(); }
' Compute feasibility relaxation for infeasible model If model.Status = GRB.Status.INFEASIBLE Then Dim vars As GRBVar() = model.GetVars() Dim ubpen As Double() = New Double(model.NumVars) For i As Integer = 0 To model.NumVars ubpen(i) = 1.0 Next model.FeasRelax(0, false, vars, Nothing, ubpen, Nothing, Nothing) model.Optimize() End If
- double FeasRelax(int relaxobjtype, boolean minrelax, boolean vrelax, boolean crelax)#
Modifies the
GRBModel
object to create a feasibility relaxation. Note that you need to callOptimize
on the result to compute the actual relaxed solution.The feasibility relaxation is a model that, when solved, minimizes the amount by which the solution violates the bounds and linear constraints of the original model. This method provides a number of options for specifying the relaxation.
If you specify
relaxobjtype=0
, the objective of the feasibility relaxation is to minimize the sum of the weighted magnitudes of the bound and constraint violations. Thelbpen
,ubpen
, andrhspen
arguments specify the cost per unit violation in the lower bounds, upper bounds, and linear constraints, respectively.If you specify
relaxobjtype=1
, the objective of the feasibility relaxation is to minimize the weighted sum of the squares of the bound and constraint violations. Thelbpen
,ubpen
, andrhspen
arguments specify the coefficients on the squares of the lower bound, upper bound, and linear constraint violations, respectively.If you specify
relaxobjtype=2
, the objective of the feasibility relaxation is to minimize the weighted count of bound and constraint violations. Thelbpen
,ubpen
, andrhspen
arguments specify the cost of violating a lower bound, upper bound, and linear constraint, respectively.To give an example, if a constraint with
rhspen
valuep
is violated by 2.0, it would contribute2*p
to the feasibility relaxation objective forrelaxobjtype=0
, it would contribute2*2*p
forrelaxobjtype=1
, and it would contributep
forrelaxobjtype=2
.The
minrelax
argument is a boolean that controls the type of feasibility relaxation that is created. Ifminrelax=false
, optimizing the returned model gives a solution that minimizes the cost of the violation. Ifminrelax=true
, optimizing the returned model finds a solution that minimizes the original objective, but only from among those solutions that minimize the cost of the violation. Note thatfeasRelax
must solve an optimization problem to find the minimum possible relaxation whenminrelax=true
, which can be quite expensive.There are two signatures for this method. The more complex one takes a list of variables and constraints, as well as penalties associated with relaxing the corresponding lower bounds, upper bounds, and constraints. If a variable or constraint is not included in one of these lists, the associated bounds or constraints may not be violated. The simpler signature takes a pair of boolean arguments,
vrelax
andcrelax
, that indicate whether variable bounds and/or constraints can be violated. Ifvrelax
/crelax
istrue
, then every bound/constraint is allowed to be violated, respectively, and the associated cost is 1.0.For an example of how this routine transforms a model, and more details about the variables and constraints created, please see this section.
Note that this is a destructive method: it modifies the model on which it is invoked. If you don’t want to modify your original model, use the
GRBModel constructor
to create a copy before invoking this method.Simplified method for creating a feasibility relaxation model.
- Parameters:
relaxobjtype – The cost function used when finding the minimum cost relaxation.
minrelax – The type of feasibility relaxation to perform.
vrelax – Indicates whether variable bounds can be relaxed (with a cost of 1.0 for any violations.
crelax – Indicates whether linear constraints can be relaxed (with a cost of 1.0 for any violations.
- Returns:
Zero if
minrelax
is false. Ifminrelax
is true, the return value is the objective value for the relaxation performed. If the value is less than 0, it indicates that the method failed to create the feasibility relaxation.- Example:
// Compute feasibility relaxation for infeasible model if (model.Status == GRB.Status.INFEASIBLE) { model.FeasRelax(1, false, false, true); model.Optimize(); }
' Compute feasibility relaxation for infeasible model If model.Status = GRB.Status.INFEASIBLE Then model.FeasRelax(1, false, false, true) model.Optimize() End If
- GRBModel FixedModel()#
Create the fixed model associated with a MIP model. A solution (e.g. obtained through a call to the
Optimize
method) or a MIP start must be available in the MIP model. If no solution is available, the MIP start specified with StartNumber is used.In the model, each integer variable is fixed to the value that variable takes in the MIP solution or MIP start. In addition, continuous variables may be fixed to satisfy SOS or general constraints. The result is that the model has neither integrality constraints, SOS constraints, nor general constraints any more.
Note
While the fixed problem is always a continuous model, it may contain a non-convex quadratic objective or non-convex quadratic constraints. As a result, it may still be solved using the MIP algorithm.
Note
On a multi-objective model, all but the first objectives are ignored. All scenarios are ignored as well, if any.
- Returns:
Fixed model associated with calling object.
- Example:
GRBModel fixedModel = model.FixedModel();
Dim fixedModel As GRBModel = model.FixedModel()
- void ConvertToFixed()#
Turn the MIP model into a continuous one, in place. A solution (e.g. obtained through a call to the
Optimize
method) or a MIP start must be available in the MIP model. If no solution is available, the MIP start specified with StartNumber is used.In the model, each integer variable is fixed to the value that variable takes in the MIP solution or MIP start. In addition, continuous variables may be fixed to satisfy SOS or general constraints. The result is that the model has neither integrality constraints, SOS constraints, nor general constraints any more.
Note
While the fixed problem is always a continuous model, it may contain a non-convex quadratic objective or non-convex quadratic constraints. As a result, it may still be solved using the MIP algorithm.
Note
An error is raised if the converted model contains more than one objective or scenario, or if the model contains concurrent environments or tune environments.
- Example:
model.ConvertToFixed();
model.ConvertToFixed()
- double Get(GRB.DoubleParam param)#
Query the value of a double-valued parameter.
- Parameters:
param – The parameter being queried.
- Returns:
The current value of the requested parameter.
- Example:
// Get value of TimeLimit parameter double val = model.Get(GRB.DoubleParam.TimeLimit);
' Get value of TimeLimit parameter Dim val As Double = model.Get(GRB.DoubleParam.TimeLimit)
- int Get(GRB.IntParam param)#
Query the value of an int-valued parameter.
- Parameters:
param – The parameter being queried.
- Returns:
The current value of the requested parameter.
- Example:
// Get value of PumpPasses parameter int val = model.Get(GRB.IntParam.PumpPasses);
' Get value of PumpPasses parameter Dim val As Integer = model.Get(GRB.IntParam.PumpPasses)
- string Get(GRB.StringParam param)#
Query the value of a string-valued parameter.
- Parameters:
param – The parameter being queried.
- Returns:
The current value of the requested parameter.
- Example:
// Get value of LogFile parameter string val = model.Get(GRB.StringParam.LogFile);
' Get value of LogFile parameter Dim val As String = model.Get(GRB.StringParam.LogFile)
- char[] Get(GRB.CharAttr attr, GRBVar[] vars)#
Query a char-valued variable attribute for an array of variables.
- Parameters:
attr – The attribute being queried.
vars – The variables whose attribute values are being queried.
- Returns:
The current values of the requested attribute for each input variable.
- Example:
// Get variable type attribute values GRBVar[] vars = model.GetVars(); char[] vtype = model.Get(GRB.CharAttr.VType, vars);
' Get variable type attribute values Dim vars As GRBVar() = model.GetVars() Dim vtype As Char() = model.Get(GRB.CharAttr.VType, vars)
- char[] Get(GRB.CharAttr attr, GRBVar[] vars, int start, int len)#
Query a char-valued variable attribute for a sub-array of variables.
- Parameters:
attr – The attribute being queried.
vars – A one-dimensional array of variables whose attribute values are being queried.
start – The index of the first variable of interest in the list.
len – The number of variables.
- Returns:
The current values of the requested attribute for each input variable.
- Example:
// Get variable type attribute values for variables indexed from 0 to 2 GRBVar[] vars = model.GetVars(); char[] vtype = model.Get(GRB.CharAttr.VType, vars, 0, 3);
' Get variable type attribute values for variables indexed from 0 to 2 Dim vars As GRBVar() = model.GetVars() Dim vtype As Char() = model.Get(GRB.CharAttr.VType, vars, 0, 3)
- char[,] Get(GRB.CharAttr attr, GRBVar[,] vars)#
Query a char-valued variable attribute for a two-dimensional array of variables.
- Parameters:
attr – The attribute being queried.
vars – A two-dimensional array of variables whose attribute values are being queried.
- Returns:
The current values of the requested attribute for each input variable.
- Example:
// Get variable type attribute values GRBVar[,] vars = new GRBVar[10, 10]; // ... char[,] vtype = model.Get(GRB.CharAttr.VType, vars);
' Get variable type attribute values Dim vars As GRBVar(,) = New GRBVar(10, 10) ' ... Dim vtype As Char(,) = model.Get(GRB.CharAttr.VType, vars)
- char[,,] Get(GRB.CharAttr attr, GRBVar[,,] vars)#
Query a char-valued variable attribute for a three-dimensional array of variables.
- Parameters:
attr – The attribute being queried.
vars – A three-dimensional array of variables whose attribute values are being queried.
- Returns:
The current values of the requested attribute for each input variable.
- Example:
// Get variable type attribute values GRBVar[,,] vars = new GRBVar[10, 10, 10]; // ... char[,,] vtype = model.Get(GRB.CharAttr.VType, vars);
' Get variable type attribute values Dim vars As GRBVar(,,) = New GRBVar(10, 10, 10) ' ... Dim vtype As Char(,,) = model.Get(GRB.CharAttr.VType, vars)
- char[] Get(GRB.CharAttr attr, GRBConstr[] constrs)#
Query a char-valued constraint attribute for an array of constraints.
- Parameters:
attr – The attribute being queried.
constrs – The constraints whose attribute values are being queried.
- Returns:
The current values of the requested attribute for each input constraint.
- Example:
// Get sense attribute values for all linear constraints GRBConstr[] constrs = model.GetConstrs(); char[] sense = model.Get(GRB.CharAttr.Sense, constrs);
' Get sense attribute values for all linear constraints Dim constrs As GRBConstr() = model.GetConstrs() Dim sense As Char() = model.Get(GRB.CharAttr.Sense, constrs)
- char[] Get(GRB.CharAttr attr, GRBConstr[] constrs, int start, int len)#
Query a char-valued constraint attribute for a sub-array of constraints.
- Parameters:
attr – The attribute being queried.
constrs – A one-dimensional array of constraints whose attribute values are being queried.
start – The index of the first constraint of interest in the list.
len – The number of constraints.
- Returns:
The current values of the requested attribute for each input constraint.
- Example:
// Get linear constraint sense attribute values for constraints indexed from 0 to 2 GRBConstr[] constrs = model.GetConstrs(); char[] sense = model.Get(GRB.CharAttr.Sense, constrs, 0, 3);
' Get linear constraint sense attribute values for constraints indexed from 0 to 2 Dim constrs As GRBConstr() = model.GetConstrs() Dim sense As Char() = model.Get(GRB.CharAttr.Sense, constrs, 0, 3)
- char[,] Get(GRB.CharAttr attr, GRBConstr[,] constrs)#
Query a char-valued constraint attribute for a two-dimensional array of constraints.
- Parameters:
attr – The attribute being queried.
constrs – A two-dimensional array of constraints whose attribute values are being queried.
- Returns:
The current values of the requested attribute for each input constraint.
- Example:
// Get linear constraint sense attribute values GRBConstr[,] constrs = new GRBConstr[10, 10]; // ... char[,] sense = model.Get(GRB.CharAttr.Sense, constrs);
' Get linear constraint sense attribute values Dim constrs As GRBConstr(,) = New GRBConstr(10, 10) ' ... Dim sense As Char(,) = model.Get(GRB.CharAttr.Sense, constrs)
- char[,,] Get(GRB.CharAttr attr, GRBConstr[,,] constrs)#
Query a char-valued constraint attribute for a three-dimensional array of constraints.
- Parameters:
attr – The attribute being queried.
constrs – A three-dimensional array of constraints whose attribute values are being queried.
- Returns:
The current values of the requested attribute for each input constraint.
- Example:
// Get linear constraint sense attribute values GRBConstr[,,] constrs = new GRBConstr[10, 10, 10]; // ... char[,,] sense = model.Get(GRB.CharAttr.Sense, constrs);
' Get linear constraint sense attribute values Dim constrs As GRBConstr(,,) = New GRBConstr(10, 10, 10) ' ... Dim sense As Char(,,) = model.Get(GRB.CharAttr.Sense, constrs)
- char[] Get(GRB.CharAttr attr, GRBQConstr[] qconstrs)#
Query a char-valued quadratic constraint attribute for an array of quadratic constraints.
- Parameters:
attr – The attribute being queried.
qconstrs – The quadratic constraints whose attribute values are being queried.
- Returns:
The current values of the requested attribute for each input quadratic constraint.
- Example:
// Get sense attribute values for all quadratic constraints GRBQConstr[] constrs = model.GetQConstrs(); char[] qsense = model.Get(GRB.CharAttr.QCSense, constrs);
' Get sense attribute values for all quadratic constraints Dim constrs As GRBQConstr() = model.GetQConstrs() Dim qsense As Char() = model.Get(GRB.CharAttr.QCSense, constrs)
- char[] Get(GRB.CharAttr attr, GRBQConstr[] qconstrs, int start, int len)#
Query a char-valued quadratic constraint attribute for a sub-array of quadratic constraints.
- Parameters:
attr – The attribute being queried.
qconstrs – A one-dimensional array of quadratic constraints whose attribute values are being queried.
start – The index of the first quadratic constraint of interest in the list.
len – The number of quadratic constraints.
- Returns:
The current values of the requested attribute for each input quadratic constraint.
- Example:
// Get sense attribute values for quadratic constraints indexed from 0 to 2 GRBQConstr[] constrs = model.GetQConstrs(); char[] qsense = model.Get(GRB.CharAttr.QCSense, constrs, 0, 3);
' Get sense attribute values for quadratic constraints indexed from 0 to 2 Dim constrs As GRBQConstr() = model.GetQConstrs() Dim qsense As Char() = model.Get(GRB.CharAttr.QCSense, constrs, 0, 3)
- char[,] Get(GRB.CharAttr attr, GRBQConstr[,] qconstrs)#
Query a char-valued quadratic constraint attribute for a two-dimensional array of quadratic constraints.
- Parameters:
attr – The attribute being queried.
qconstrs – A two-dimensional array of quadratic constraints whose attribute values are being queried.
- Returns:
The current values of the requested attribute for each input quadratic constraint.
- Example:
// Get sense attribute values GRBQConstr[,] constrs = new GRBQConstr[10, 10]; // ... char[,] qsense = model.Get(GRB.CharAttr.QCSense, constrs);
' Get sense attribute values Dim constrs As GRBQConstr(,) = New GRBQConstr(10, 10) ' ... Dim qsense As Char(,) = model.Get(GRB.CharAttr.QCSense, constrs)
- char[,,] Get(GRB.CharAttr attr, GRBQConstr[,,] qconstrs)#
Query a char-valued quadratic constraint attribute for a three-dimensional array of quadratic constraints.
- Parameters:
attr – The attribute being queried.
qconstrs – A three-dimensional array of quadratic constraints whose attribute values are being queried.
- Returns:
The current values of the requested attribute for each input quadratic constraint.
- Example:
// Get sense attribute values GRBQConstr[,,] constrs = new GRBQConstr[10, 10, 10]; // ... char[,,] qsense = model.Get(GRB.CharAttr.QCSense, constrs);
' Get sense attribute values Dim constrs As GRBQConstr(,,) = New GRBQConstr(10, 10, 10) ' ... Dim qsense As Char(,,) = model.Get(GRB.CharAttr.QCSense, constrs)
- char[,,] Get(GRB.CharAttr attr, GRBQConstr[,,] qconstrs)#
- double Get(GRB.DoubleAttr attr)#
Query the value of a double-valued model attribute.
- Parameters:
attr – The attribute being queried.
- Returns:
The current value of the requested attribute.
- Example:
// Get value ObjVal attribute double val = model.Get(GRB.DoubleAttr.ObjVal);
' Get value ObjVal attribute Dim val As Double = model.Get(GRB.DoubleAttr.ObjVal)
- double[] Get(GRB.DoubleAttr attr, GRBVar[] vars)#
Query a double-valued variable attribute for an array of variables.
- Parameters:
attr – The attribute being queried.
vars – The variables whose attribute values are being queried.
- Returns:
The current values of the requested attribute for each input variable.
- Example:
// Get lower bound attribute values of all variables GRBVar[] vars = model.GetVars(); double[] lb = model.Get(GRB.DoubleAttr.LB, vars);
' Get lower bound attribute values of all variables Dim vars As GRBVar() = model.GetVars() Dim lb As Double() = model.Get(GRB.DoubleAttr.LB, vars)
- double[] Get(GRB.DoubleAttr attr, GRBVar[] vars, int start, int len)#
Query a double-valued variable attribute for a sub-array of variables.
- Parameters:
attr – The attribute being queried.
vars – A one-dimensional array of variables whose attribute values are being queried.
start – The index of the first variable of interest in the list.
len – The number of variables.
- Returns:
The current values of the requested attribute for each input variable.
- Example:
// Get lower bound attribute values for variables indexed from 0 to 2 GRBVar[] vars = model.GetVars(); double[] lb = model.Get(GRB.DoubleAttr.LB, vars, 0, 3);
' Get lower bound attribute values for variables indexed from 0 to 2 Dim vars As GRBVar() = model.GetVars() Dim lb As Double() = model.Get(GRB.DoubleAttr.LB, vars, 0, 3)
- double[,] Get(GRB.DoubleAttr attr, GRBVar[,] vars)#
Query a double-valued variable attribute for a two-dimensional array of variables.
- Parameters:
attr – The attribute being queried.
vars – A two-dimensional array of variables whose attribute values are being queried.
- Returns:
The current values of the requested attribute for each input variable.
- Example:
// Get lower bound attribute values GRBVar[,] vars = new GRBVar[10, 10]; // ... double[,] lb = model.Get(GRB.DoubleAttr.LB, vars);
' Get lower bound attribute values Dim vars As GRBVar(,) = New GRBVar(10, 10) ' ... Dim lb As Double(,) = model.Get(GRB.DoubleAttr.LB, vars)
- double[,,] Get(GRB.DoubleAttr attr, GRBVar[,,] vars)#
Query a double-valued variable attribute for a three-dimensional array of variables.
- Parameters:
attr – The attribute being queried.
vars – A three-dimensional array of variables whose attribute values are being queried.
- Returns:
The current values of the requested attribute for each input variable.
- Example:
// Get lower bound attribute values GRBVar[,,] vars = new GRBVar[10, 10, 10]; // ... double[,,] lb = model.Get(GRB.DoubleAttr.LB, vars);
' Get lower bound attribute values Dim vars As GRBVar(,,) = New GRBVar(10, 10, 10) ' ... Dim lb As Double(,,) = model.Get(GRB.DoubleAttr.LB, vars)
- double[] Get(GRB.DoubleAttr attr, GRBConstr[] constrs)#
Query a double-valued constraint attribute for an array of constraints.
- Parameters:
attr – The attribute being queried.
constrs – The constraints whose attribute values are being queried.
- Returns:
The current values of the requested attribute for each input constraint.
- Example:
// Get RHS attribute values of all linear constraints GRBConstr[] constrs = model.GetConstrs(); double[] rhs = model.Get(GRB.DoubleAttr.RHS, constrs);
' Get RHS attribute values of all linear constraints Dim constrs As GRBConstr() = model.GetConstrs() Dim rhs As Double() = model.Get(GRB.DoubleAttr.RHS, constrs)
- double[] Get(GRB.DoubleAttr attr, GRBConstr[] constrs, int start, int len)#
Query a double-valued constraint attribute for a sub-array of constraints.
- Parameters:
attr – The attribute being queried.
constrs – A one-dimensional array of constraints whose attribute values are being queried.
start – The first constraint of interest in the list.
len – The number of constraints.
- Returns:
The current values of the requested attribute for each input constraint.
- Example:
// Get RHS attribute values for linear constraints indexed from 0 to 2 GRBConstr[] constrs = model.GetConstrs(); double[] rhs = model.Get(GRB.DoubleAttr.RHS, constrs, 0, 3);
' Get RHS attribute values for linear constraints indexed from 0 to 2 Dim constrs As GRBConstr() = model.GetConstrs() Dim rhs As Double() = model.Get(GRB.DoubleAttr.RHS, constrs, 0, 3)
- double[,] Get(GRB.DoubleAttr attr, GRBConstr[,] constrs)#
Query a double-valued constraint attribute for a two-dimensional array of constraints.
- Parameters:
attr – The attribute being queried.
constrs – A two-dimensional array of constraints whose attribute values are being queried.
- Returns:
The current values of the requested attribute for each input constraint.
- Example:
// Get RHS attribute values GRBConstr[,] constrs = new GRBConstr[10, 10]; // ... double[,] rhs = model.Get(GRB.DoubleAttr.RHS, constrs);
' Get RHS attribute values Dim constrs As GRBConstr(,) = New GRBConstr(10, 10) ' ... Dim rhs As Double(,) = model.Get(GRB.DoubleAttr.RHS, constrs)
- double[,,] Get(GRB.DoubleAttr attr, GRBConstr[,,] constrs)#
Query a double-valued constraint attribute for a three-dimensional array of constraints.
- Parameters:
attr – The attribute being queried.
constrs – A three-dimensional array of constraints whose attribute values are being queried.
- Returns:
The current values of the requested attribute for each input constraint.
- Example:
// Get RHS attribute values GRBConstr[,,] constrs = new GRBConstr[10, 10, 10]; // ... double[,,] rhs = model.Get(GRB.DoubleAttr.RHS, constrs);
' Get RHS attribute values Dim constrs As GRBConstr(,,) = New GRBConstr(10, 10, 10) ' ... Dim rhs As Double(,,) = model.Get(GRB.DoubleAttr.RHS, constrs)
- double[] Get(GRB.DoubleAttr attr, GRBQConstr[] qconstrs)#
Query a double-valued quadratic constraint attribute for an array of quadratic constraints.
- Parameters:
attr – The attribute being queried.
qconstrs – The quadratic constraints whose attribute values are being queried.
- Returns:
The current values of the requested attribute for each input quadratic constraint.
- Example:
// Get RHS attribute values of all quadratic constraints GRBQConstr[] constrs = model.GetQConstrs(); double[] qrhs = model.Get(GRB.DoubleAttr.QCRHS, constrs);
' Get RHS attribute values of all quadratic constraints Dim constrs As GRBQConstr() = model.GetQConstrs() Dim qcrs As Double() = model.Get(GRB.DoubleAttr.QCRHS, constrs)
- double[] Get(GRB.DoubleAttr attr, GRBQConstr[] qconstrs, int start, int len)#
Query a double-valued quadratic constraint attribute for a sub-array of quadratic constraints.
- Parameters:
attr – The attribute being queried.
qconstrs – A one-dimensional array of quadratic constraints whose attribute values are being queried.
start – The first quadratic constraint of interest in the list.
len – The number of quadratic constraints.
- Returns:
The current values of the requested attribute for each input quadratic constraint.
- Example:
// Get RHS attribute values for quadratic constraints indexed from 0 to 2 GRBQConstr[] constrs = model.GetQConstrs(); double[] qrhs = model.Get(GRB.DoubleAttr.QCRHS, constrs, 0, 3);
' Get RHS attribute values for quadratic constraints indexed from 0 to 2 Dim constrs As GRBQConstr() = model.GetQConstrs() Dim qcrs As Double() = model.Get(GRB.DoubleAttr.QCRHS, constrs, 0, 3)
- double[,] Get(GRB.DoubleAttr attr, GRBQConstr[,] qconstrs)#
Query a double-valued quadratic constraint attribute for a two-dimensional array of quadratic constraints.
- Parameters:
attr – The attribute being queried.
qconstrs – A two-dimensional array of quadratic constraints whose attribute values are being queried.
- Returns:
The current values of the requested attribute for each input quadratic constraint.
- Example:
// Get RHS attribute values GRBQConstr[,] constrs = new GRBQConstr[10, 10]; // .. double[,] qrhs = model.Get(GRB.DoubleAttr.QCRHS, constrs);
' Get RHS attribute values Dim constrs As GRBQConstr(,) = New GRBQConstr(10, 10) ' .. Dim qrhs As Double(,) = model.Get(GRB.DoubleAttr.QCRHS, constrs)
- double[,,] Get(GRB.DoubleAttr attr, GRBQConstr[,,] qconstrs)#
Query a double-valued quadratic constraint attribute for a three-dimensional array of quadratic constraints.
- Parameters:
attr – The attribute being queried.
qconstrs – A three-dimensional array of quadratic constraints whose attribute values are being queried.
- Returns:
The current values of the requested attribute for each input quadratic constraint.
- Example:
// Get RHS attribute values GRBQConstr[,,] constrs = new GRBQConstr[10, 10, 10]; // .. double[,,] qrhs = model.Get(GRB.DoubleAttr.QCRHS, constrs);
' Get RHS attribute values Dim constrs As GRBQConstr(,,) = New GRBQConstr(10, 10, 10) ' .. Dim qrhs As Double(,,) = model.Get(GRB.DoubleAttr.QCRHS, constrs)
- int Get(GRB.IntAttr attr)#
Query the value of an int-valued model attribute.
- Parameters:
attr – The attribute being queried.
- Returns:
The current value of the requested attribute.
- Example:
// Get number of variables in the model int numvars = model.Get(GRB.IntAttr.NumVars);
' Get number of variables in the model Dim numvars As Integer = model.Get(GRB.IntAttr.NumVars)
- int[] Get(GRB.IntAttr attr, GRBVar[] vars)#
Query an int-valued variable attribute for an array of variables.
- Parameters:
attr – The attribute being queried.
vars – The variables whose attribute values are being queried.
- Returns:
The current values of the requested attribute for each input variable.
- Example:
// Get VBasis attribute values of all variables GRBVar[] vars = model.GetVars(); int[] vbasis = model.Get(GRB.IntAttr.VBasis, vars);
' Get VBasis attribute values of all variables Dim vars As GRBVar() = model.GetVars() Dim vbasis As Integer() = model.Get(GRB.IntAttr.VBasis, vars)
- int[] Get(GRB.IntAttr attr, GRBVar[] vars, int start, int len)#
Query an int-valued variable attribute for a sub-array of variables.
- Parameters:
attr – The attribute being queried.
vars – A one-dimensional array of variables whose attribute values are being queried.
start – The index of the first variable of interest in the list.
len – The number of variables.
- Returns:
The current values of the requested attribute for each input variable.
- Example:
// Get VBasis attribute values for variables indexed from 0 to 2 GRBVar[] vars = model.GetVars(); int[] vbasis = model.Get(GRB.IntAttr.VBasis, vars, 0, 3);
' Get VBasis attribute values for variables indexed from 0 to 2 Dim vars As GRBVar() = model.GetVars() Dim vbasis As Integer() = model.Get(GRB.IntAttr.VBasis, vars, 0, 3)
- int[,] Get(GRB.IntAttr attr, GRBVar[,] vars)#
Query an int-valued variable attribute for a two-dimensional array of variables.
- Parameters:
attr – The attribute being queried.
vars – A two-dimensional array of variables whose attribute values are being queried.
- Returns:
The current values of the requested attribute for each input variable.
- Example:
// Get VBasis attribute values GRBVar[,] vars = new GRBVar[10, 10]; // ... int[,] vbasis = model.Get(GRB.IntAttr.VBasis, vars);
' Get VBasis attribute values Dim vars As GRBVar(,) = new GRBVar(10, 10) ' ... Dim vbasis As Integer(,) = model.Get(GRB.IntAttr.VBasis, vars)
- int[,,] Get(GRB.IntAttr attr, GRBVar[,,] vars)#
Query an int-valued variable attribute for a three-dimensional array of variables.
- Parameters:
attr – The attribute being queried.
vars – A three-dimensional array of variables whose attribute values are being queried.
- Returns:
The current values of the requested attribute for each input variable.
- Example:
// Get VBasis attribute values GRBVar[,,] vars = new GRBVar[10, 10, 10]; // ... int[,,] vbasis = model.Get(GRB.IntAttr.VBasis, vars);
' Get VBasis attribute values Dim vars As GRBVar(,,) = new GRBVar(10, 10, 10) ' ... Dim vbasis As Integer(,,) = model.Get(GRB.IntAttr.VBasis, vars)
- int[] Get(GRB.IntAttr attr, GRBConstr[] constrs)#
Query an int-valued constraint attribute for an array of constraints.
- Parameters:
attr – The attribute being queried.
constrs – The constraints whose attribute values are being queried.
- Returns:
The current values of the requested attribute for each input constraint.
- Example:
// Get CBasis attribute values of all linear constraints GRBConstr[] constrs = model.GetConstrs(); int[] cbasis = model.Get(GRB.IntAttr.CBasis, constrs);
' Get CBasis attribute values of all linear constraints Dim constrs As GRBConstr() = model.GetConstrs() Dim cbasis As Integer() = model.Get(GRB.IntAttr.CBasis, constrs)
- int[] Get(GRB.IntAttr attr, GRBConstr[] constrs, int start, int len)#
Query an int-valued constraint attribute for a sub-array of constraints.
- Parameters:
attr – The attribute being queried.
constrs – A one-dimensional array of constraints whose attribute values are being queried.
start – The index of the first constraint of interest in the list.
len – The number of constraints.
- Returns:
The current values of the requested attribute for each input constraint.
- Example:
// Get CBasis attribute values for linear constraints indexed from 0 to 2 GRBConstr[] constrs = model.GetConstrs(); int[] cbasis = model.Get(GRB.IntAttr.CBasis, constrs, 0, 3);
' Get CBasis attribute values for linear constraints indexed from 0 to 2 Dim constrs As GRBConstr() = model.GetConstrs() Dim cbasis As Integer() = model.Get(GRB.IntAttr.CBasis, constrs, 0, 3)
- int[,] Get(GRB.IntAttr attr, GRBConstr[,] constrs)#
Query an int-valued constraint attribute for a two-dimensional array of constraints.
- Parameters:
attr – The attribute being queried.
constrs – A two-dimensional array of constraints whose attribute values are being queried.
- Returns:
The current values of the requested attribute for each input constraint.
- Example:
// Get CBasis attribute values GRBConstr[,] constrs = new GRBConstr[10, 10]; // ... int[,] cbasis = model.Get(GRB.IntAttr.CBasis, constrs);
' Get CBasis attribute values Dim constrs As GRBConstr(,) = New GRBConstr(10, 10) ' ... Dim cbasis As Integer(,) = model.Get(GRB.IntAttr.CBasis, constrs)
- int[,,] Get(GRB.IntAttr attr, GRBConstr[,,] constrs)#
Query an int-valued constraint attribute for a three-dimensional array of constraints.
- Parameters:
attr – The attribute being queried.
constrs – A three-dimensional array of constraints whose attribute values are being queried.
- Returns:
The current values of the requested attribute for each input constraint.
- Example:
// Get CBasis attribute values GRBConstr[,,] constrs = new GRBConstr[10, 10, 10]; // ... int[,,] cbasis = model.Get(GRB.IntAttr.CBasis, constrs);
' Get CBasis attribute values Dim constrs As GRBConstr(,,) = New GRBConstr(10, 10, 10) ' ... Dim cbasis As Integer(,,) = model.Get(GRB.IntAttr.CBasis, constrs)
- string Get(GRB.StringAttr attr)#
Query the value of a string-valued model attribute.
- Parameters:
attr – The attribute being queried.
- Returns:
The current value of the requested attribute.
- Example:
// Get ModelName attribute string modelname = model.Get(GRB.StringAttr.ModelName);
' Get ModelName attribute Dim modelname As String = model.Get(GRB.StringAttr.ModelName)
- string[] Get(GRB.StringAttr attr, GRBVar[] vars)#
Query a string-valued variable attribute for an array of variables.
- Parameters:
attr – The attribute being queried.
vars – The variables whose attribute values are being queried.
- Returns:
The current values of the requested attribute for each input variable.
- Example:
// Get variable name attribute values of all variables GRBVar[] vars = model.GetVars(); string[] varNames = model.Get(GRB.StringAttr.VarName, vars);
' Get variable name attribute values of all variables Dim vars As GRBVar() = model.GetVars() Dim varNames As String() = model.Get(GRB.StringAttr.VarName, vars)
- string[] Get(GRB.StringAttr attr, GRBVar[] vars, int start, int len)#
Query a string-valued variable attribute for a sub-array of variables.
- Parameters:
attr – The attribute being queried.
vars – A one-dimensional array of variables whose attribute values are being queried.
start – The index of the first variable of interest in the list.
len – The number of variables.
- Returns:
The current values of the requested attribute for each input variable.
- Example:
// Get variable name attribute values for variables indexed from 0 to 2 GRBVar[] vars = model.GetVars(); string[] varNames = model.Get(GRB.StringAttr.VarName, vars, 0, 3);
' Get variable name attribute values for variables indexed from 0 to 2 Dim vars As GRBVar() = model.GetVars() Dim varNames As String() = model.Get(GRB.StringAttr.VarName, vars, 0, 3)
- string[,] Get(GRB.StringAttr attr, GRBVar[,] vars)#
Query a string-valued variable attribute for a two-dimensional array of variables.
- Parameters:
attr – The attribute being queried.
vars – A two-dimensional array of variables whose attribute values are being queried.
- Returns:
The current values of the requested attribute for each input variable.
- Example:
// Get variable name attribute GRBVar[,] vars = new GRBVar[10, 10]; // ... string[,] varNames = model.Get(GRB.StringAttr.VarName, vars);
' Get variable name attribute Dim vars As GRBVar(,) = new GRBVar(10, 10) ' ... Dim varNames As String(,) = model.Get(GRB.StringAttr.VarName, vars)
- string[,,] Get(GRB.StringAttr attr, GRBVar[,,] vars)#
Query a string-valued variable attribute for a three-dimensional array of variables.
- Parameters:
attr – The attribute being queried.
vars – A three-dimensional array of variables whose attribute values are being queried.
- Returns:
The current values of the requested attribute for each input variable.
- Example:
// Get variable name attribute GRBVar[,,] vars = new GRBVar[10, 10, 10]; // ... string[,,] varNames = model.Get(GRB.StringAttr.VarName, vars);
' Get variable name attribute Dim vars As GRBVar(,,) = new GRBVar(10, 10, 10) ' ... Dim varNames As String(,,) = model.Get(GRB.StringAttr.VarName, vars)
- string[] Get(GRB.StringAttr attr, GRBConstr[] constrs)#
Query a string-valued constraint attribute for an array of constraints.
- Parameters:
attr – The attribute being queried.
constrs – The constraints whose attribute values are being queried.
- Returns:
The current values of the requested attribute for each input constraint.
- Example:
// Get constraint name attribute values of all linear constraints GRBConstr[] constrs = model.GetConstrs(); string[] constrNames = model.Get(GRB.StringAttr.ConstrName, constrs);
' Get constraint name attribute values of all linear constraints Dim constrs As GRBConstr() = model.GetConstrs() Dim constrNames As String() = model.Get(GRB.StringAttr.ConstrName, constrs)
- string[] Get(GRB.StringAttr attr, GRBConstr[] constrs, int start, int len)#
Query a string-valued constraint attribute for a sub-array of constraints.
- Parameters:
attr – The attribute being queried.
constrs – A one-dimensional array of constraints whose attribute values are being queried.
start – The index of the first constraint of interest in the list.
len – The number of constraints.
- Returns:
The current values of the requested attribute for each input constraint.
- Example:
// Get constraint name attribute values for linear constraints indexed from 0 to 2 GRBConstr[] constrs = model.GetConstrs(); string[] constrNames = model.Get(GRB.StringAttr.ConstrName, constrs, 0, 3);
' Get constraint name attribute values for linear constraints indexed from 0 to 2 Dim constrs As GRBConstr() = model.GetConstrs() Dim constrNames As String() = model.Get(GRB.StringAttr.ConstrName, constrs, 0, 3)
- string[,] Get(GRB.StringAttr attr, GRBConstr[,] constrs)#
Query a string-valued constraint attribute for a two-dimensional array of constraints.
- Parameters:
attr – The attribute being queried.
constrs – A two-dimensional array of constraints whose attribute values are being queried.
- Returns:
The current values of the requested attribute for each input constraint.
- Example:
// Get constraint name attribute values GRBConstr[,] constrs = new GRBConstr[10, 10]; // ... string[,] constrNames = model.Get(GRB.StringAttr.ConstrName, constrs);
' Get constraint name attribute values Dim constrs As GRBConstr(,) = New GRBConstr(10, 10) ' ... Dim constrNames As String(,) = model.Get(GRB.StringAttr.ConstrName, constrs)
- string[,,] Get(GRB.StringAttr attr, GRBConstr[,,] constrs)#
Query a string-valued constraint attribute for a three-dimensional array of constraints.
- Parameters:
attr – The attribute being queried.
constrs – A three-dimensional array of constraints whose attribute values are being queried.
- Returns:
The current values of the requested attribute for each input constraint.
- Example:
// Get constraint name attribute values GRBConstr[,,] constrs = new GRBConstr[10, 10, 10]; // ... string[,,] constrNames = model.Get(GRB.StringAttr.ConstrName, constrs);
' Get constraint name attribute values Dim constrs As GRBConstr(,,) = New GRBConstr(10, 10, 10) ' ... Dim constrNames As String(,,) = model.Get(GRB.StringAttr.ConstrName, constrs)
- string[] Get(GRB.StringAttr attr, GRBQConstr[] qconstrs)#
Query a string-valued quadratic constraint attribute for an array of quadratic constraints.
- Parameters:
attr – The attribute being queried.
qconstrs – The quadratic constraints whose attribute values are being queried.
- Returns:
The current values of the requested attribute for each input quadratic constraint.
- Example:
// Get constraint name values of all quadratic constraints GRBQConstr[] constrs = model.GetQConstrs(); string[] constrNames = model.Get(GRB.StringAttr.QCName, constrs);
' Get constraint name values of all quadratic constraints Dim constrs As GRBQConstr() = model.GetQConstrs() Dim constrNames As String() = model.Get(GRB.StringAttr.QCName, constrs)
- string[] Get(GRB.StringAttr attr, GRBQConstr[] qconstrs, int start, int len)#
Query a string-valued quadratic constraint attribute for a sub-array of quadratic constraints.
- Parameters:
attr – The attribute being queried.
qconstrs – A one-dimensional array of quadratic constraints whose attribute values are being queried.
start – The index of the first quadratic constraint of interest in the list.
len – The number of quadratic constraints.
- Returns:
The current values of the requested attribute for each input quadratic constraint.
- Example:
// Get constraint name values for quadratic constraints indexed from 0 to 2 GRBQConstr[] constrs = model.GetQConstrs(); string[] constrNames = model.Get(GRB.StringAttr.QCName, constrs, 0, 3);
' Get constraint name values for quadratic constraints indexed from 0 to 2 Dim constrs As GRBQConstr() = model.GetQConstrs() Dim constrNames As String() = model.Get(GRB.StringAttr.QCName, constrs, 0, 3)
- string[,] Get(GRB.StringAttr attr, GRBQConstr[,] qconstrs)#
Query a string-valued quadratic constraint attribute for a two-dimensional array of quadratic constraints.
- Parameters:
attr – The attribute being queried.
qconstrs – A two-dimensional array of quadratic constraints whose attribute values are being queried.
- Returns:
The current values of the requested attribute for each input quadratic constraint.
- Example:
// Get constraint name values GRBQConstr[,] constrs = new GRBQConstr[10, 10]; // ... string[,] constrNames = model.Get(GRB.StringAttr.QCName, constrs);
' Get constraint name values Dim constrs As GRBQConstr(,) = New GRBQConstr(10, 10) ' ... Dim constrNames As String(,) = model.Get(GRB.StringAttr.QCName, constrs)
- string[,,] Get(GRB.StringAttr attr, GRBQConstr[,,] qconstrs)#
Query a string-valued quadratic constraint attribute for a three-dimensional array of quadratic constraints.
- Parameters:
attr – The attribute being queried.
qconstrs – A three-dimensional array of quadratic constraints whose attribute values are being queried.
- Returns:
The current values of the requested attribute for each input quadratic constraint.
- Example:
// Get constraint name values GRBQConstr[,,] constrs = new GRBQConstr[10, 10, 10]; // ... string[,,] constrNames = model.Get(GRB.StringAttr.QCName, constrs);
' Get constraint name values Dim constrs As GRBQConstr(,,) = New GRBQConstr(10, 10, 10) ' ... Dim constrNames As String(,,) = model.Get(GRB.StringAttr.QCName, constrs)
- string[,,] Get(GRB.StringAttr attr, GRBQConstr[,,] qconstrs)#
- double GetCoeff(GRBConstr constr, GRBVar var)#
Query the coefficient of variable
var
in linear constraintconstr
(note that the result can be zero).- Parameters:
constr – The requested constraint.
var – The requested variable.
- Returns:
The current value of the requested coefficient.
- Example:
// Get coefficient of variable x in constraint c1 double coeff = model.GetCoeff(c1, x);
' Get coefficient of variable x in constraint c1 Dim coeff As Double = model.GetCoeff(c1, x)
- GRBColumn GetCol(GRBVar var)#
Retrieve the list of constraints in which a variable participates, and the associated coefficients. The result is returned as a
GRBColumn
object.- Parameters:
var – The variable of interest.
- Returns:
A
GRBColumn
object that captures the set of constraints in which the variable participates.- Example:
// Get column of coefficient and constraint pairs for variable x GRBColumn col = model.GetCol(x);
' Get column of coefficient and constraint pairs for variable x Dim col As GRBColumn = model.GetCol(x)
- GRBEnv GetConcurrentEnv(int num)#
Create/retrieve a concurrent environment for a model.
This method provides fine-grained control over the concurrent optimizer. By creating your own concurrent environments and setting appropriate parameters on these environments (e.g., the Method parameter), you can control exactly which strategies the concurrent optimizer employs. For example, if you create two concurrent environments, and set Method to primal simplex for one and dual simplex for the other, subsequent concurrent optimizer runs will use the two simplex algorithms rather than the default choices.
Note that you must create contiguously numbered concurrent environments, starting with
num=0
. For example, if you want three concurrent environments, they must be numbered 0, 1, and 2.Once you create concurrent environments, they will be used for every subsequent concurrent optimization on that model. Use
DiscardConcurrentEnvs
to revert back to default concurrent optimizer behavior.- Parameters:
num – The concurrent environment number.
- Returns:
The concurrent environment for the model.
- Example:
env0 = model.GetConcurrentEnv(0); env1 = model.GetConcurrentEnv(1); env0.Set(GRB.IntParam.Method, 0); env1.Set(GRB.IntParam.Method, 1); model.Optimize(); model.DiscardConcurrentEnvs();
env0 = model.GetConcurrentEnv(0) env1 = model.GetConcurrentEnv(1) env0.Set(GRB.IntParam.Method, 0) env1.Set(GRB.IntParam.Method, 1) model.Optimize() model.DiscardConcurrentEnvs()
- GRBConstr GetConstrByName(string name)#
Retrieve a linear constraint from its name. If multiple linear constraints have the same name, this method chooses one arbitrarily.
- Parameters:
name – The name of the desired linear constraint.
- Returns:
The requested linear constraint.
- Example:
// Retrieve linear constraint named "constr1" GRBConstr c1 = model.GetConstrByName("constr1");
' Retrieve linear constraint named "constr1" Dim c1 As GRBConstr = model.GetConstrByName("constr1")
- GRBConstr[] GetConstrs()#
Retrieve an array of all linear constraints in the model.
- Returns:
All linear constraints in the model.
- Example:
// Retrieve all linear constraints GRBConstr[] constrs = model.GetConstrs();
' Retrieve all linear constraints Dim constrs As GRBConstr() = model.GetConstrs()
- void GetGenConstrMax(GRBGenConstr genc, out GRBVar resvar, out GRBVar[] vars, out double constant)#
Retrieve the data associated with a general constraint of type MAX. Calling this method for a general constraint of a different type leads to an exception. You can query the GenConstrType attribute to determine the type of the general constraint.
See also
AddGenConstrMax
for a description of the semantics of this general constraint type.- Parameters:
genc – The general constraint object.
resvar – Stores the resultant variable of the constraint.
vars – Stores the array of operand variables of the constraint.
constant – Stores the additional constant operand of the constraint.
- Example:
GRBVar resvar; GRBVar[] vars; double constant; // Retrieve general constraint type int type = genc.Get(GRB.IntAttr.GenConstrType); if (type == GRB.GENCONSTR_MAX) { // Retrieve data for given max constraint model.GetGenConstrMax(genc, out resvar, out vars, out constant); }
Dim resvar As GRBVar Dim vars As GRBVar() Dim constant As Double = 0.0 ' Retrieve general constraint type Dim type as Integer = genc.Get(GRB.IntAttr.GenConstrType) If type = GRB.GENCONSTR_MAX Then ' Retrieve data for given max constraint model.GetGenConstrMax(genc, resvar, vars, constant ) End If
- void GetGenConstrMin(GRBGenConstr genc, out GRBVar resvar, out GRBVar[] vars, out double constant)#
Retrieve the data associated with a general constraint of type MIN. Calling this method for a general constraint of a different type leads to an exception. You can query the GenConstrType attribute to determine the type of the general constraint.
See also
AddGenConstrMin
for a description of the semantics of this general constraint type.- Parameters:
genc – The general constraint object.
resvar – Stores the resultant variable of the constraint.
vars – Stores the array of operand variables of the constraint.
constant – Stores the additional constant operand of the constraint.
- Example:
GRBVar resvar; GRBVar[] vars; double constant; // Retrieve general constraint type int type = genc.Get(GRB.IntAttr.GenConstrType); if (type == GRB.GENCONSTR_MIN) { // Retrieve data for given min constraint model.GetGenConstrMin(genc, out resvar, out vars, out constant); }
Dim resvar As GRBVar Dim vars As GRBVar() Dim constant As Double = 0.0 ' Retrieve general constraint type Dim type as Integer = genc.Get(GRB.IntAttr.GenConstrType) If type = GRB.GENCONSTR_MIN Then ' Retrieve data for given min constraint model.GetGenConstrMin(genc, resvar, vars, constant) End If
- void GetGenConstrAbs(GRBGenConstr genc, out GRBVar resvar, out GRBVar argvar)#
Retrieve the data associated with a general constraint of type ABS. Calling this method for a general constraint of a different type leads to an exception. You can query the GenConstrType attribute to determine the type of the general constraint.
See also
AddGenConstrAbs
for a description of the semantics of this general constraint type.- Parameters:
genc – The general constraint object.
resvar – Stores the resultant variable of the constraint.
argvar – Stores the argument variable of the constraint.
- Example:
GRBVar resvar; GRBVar argvar; // Retrieve general constraint type int type = genc.Get(GRB.IntAttr.GenConstrType); if (type == GRB.GENCONSTR_ABS) { // Retrieve data for given abs constraint model.GetGenConstrAbs(genc, out resvar, out argvar); }
Dim resvar As GRBVar Dim argvar As GRBVar ' Retrieve general constraint type Dim type as Integer = genc.Get(GRB.IntAttr.GenConstrType) If type = GRB.GENCONSTR_ABS Then ' Retrieve data for given abs constraint model.GetGenConstrAbs(genc, resvar, argvar) End If
- void GetGenConstrAnd(GRBGenConstr genc, out GRBVar resvar, out GRBVar[] vars)#
Retrieve the data associated with a general constraint of type AND. Calling this method for a general constraint of a different type leads to an exception. You can query the GenConstrType attribute to determine the type of the general constraint.
See also
AddGenConstrAnd
for a description of the semantics of this general constraint type.- Parameters:
genc – The general constraint object.
resvar – Stores the resultant variable of the constraint.
vars – Stores the array of operand variables of the constraint.
- Example:
GRBVar resvar; GRBVar[] vars; // Retrieve general constraint type int type = genc.Get(GRB.IntAttr.GenConstrType); if (type == GRB.GENCONSTR_AND) { // Retrieve data for given AND constraint model.GetGenConstrAnd(genc, out resvar, out vars); }
Dim resvar As GRBVar Dim vars As GRBVar() ' Retrieve general constraint type Dim type as Integer = genc.Get(GRB.IntAttr.GenConstrType) If type = GRB.GENCONSTR_AND Then ' Retrieve data for given AND constraint model.GetGenConstrAnd(genc, resvar, vars) End If
- void GetGenConstrOr(GRBGenConstr genc, out GRBVar resvar, out GRBVar[] vars)#
Retrieve the data associated with a general constraint of type OR. Calling this method for a general constraint of a different type leads to an exception. You can query the GenConstrType attribute to determine the type of the general constraint.
See also
AddGenConstrOr
for a description of the semantics of this general constraint type.- Parameters:
genc – The general constraint object.
resvar – Stores the resultant variable of the constraint.
vars – Stores the array of operand variables of the constraint.
- Example:
GRBVar resvar; GRBVar[] vars; // Retrieve general constraint type int type = genc.Get(GRB.IntAttr.GenConstrType); if (type == GRB.GENCONSTR_OR) { // Retrieve data for given OR constraint model.GetGenConstrOr(genc, out resvar, out vars); }
Dim resvar As GRBVar Dim vars As GRBVar() ' Retrieve general constraint type Dim type as Integer = genc.Get(GRB.IntAttr.GenConstrType) If type = GRB.GENCONSTR_OR Then ' Retrieve data for given OR constraint model.GetGenConstrOr(genc, resvar, vars) End If
- void GetGenConstrNorm(GRBGenConstr genc, out GRBVar resvar, out GRBVar[] vars, out double which)#
Retrieve the data associated with a general constraint of type NORM. Calling this method for a general constraint of a different type leads to an exception. You can query the GenConstrType attribute to determine the type of the general constraint.
See also
AddGenConstrNorm
for a description of the semantics of this general constraint type.- Parameters:
genc – The general constraint object.
resvar – Stores the resultant variable of the constraint.
vars – Stores the array of operand variables of the constraint.
which – Stores the norm type (possible values are 0, 1, 2, or GRB.INFINITY).
- Example:
GRBVar resvar; GRBVar[] vars; double which; // Retrieve general constraint type int type = genc.Get(GRB.IntAttr.GenConstrType); if (type == GRB.GENCONSTR_NORM) { // Retrieve data for given norm constraint model.GetGenConstrNorm(genc, out resvar, out vars, out which); }
Dim resvar As GRBVar Dim vars As GRBVar() Dim which As Double = 0.0 ' Retrieve general constraint type Dim type as Integer = genc.Get(GRB.IntAttr.GenConstrType) If type = GRB.GENCONSTR_NORM Then ' Retrieve data for given norm constraint model.GetGenConstrNorm(genc, resvar, vars, which) End If
- void GetGenConstrNL(GRBGenConstr genc, out GRBVar resvar, out int nnodes, int[] opcode, double[] data, int[] parent)#
Retrieve the data associated with a general constraint of type NL. Calling this method for a general constraint of a different type leads to an exception. You can query the GenConstrType attribute to determine the type of the general constraint.
Typical usage is to call this routine twice. In the first call, you specify the requested general constraint, with a
null
value for theopcode
,data
andparent
arguments. The routine returns the total number of nodes that form the expression tree for the specified general constraint innnodes
. That allows you to make certain that theopcode
,data
andparent
arrays are of sufficient size to hold the result of the second call.See also
AddGenConstrNL
for a description of the semantics of this general constraint type.- Parameters:
genc – The general constraint object.
resvar – Stores the resultant variable of the constraint.
nnodes – Stores the number of nodes required to describe the nonlinear expression.
opcode – Stores the array containing the operation codes for the nodes.
data – Stores the array containing auxiliary data for each node.
parent – Stores the array providing the parent index of each node.
- Example:
GRBVar resvar; int nnodes; int[] opcode; double[] data; int[] parent; // Retrieve general constraint type int type = genc.Get(GRB.IntAttr.GenConstrType); if (type == GRB.GENCONSTR_NL) { // Get number of nodes model.GetGenConstrNL(genc, out resvar, out nnodes, null, null, null); // Initialize correct array sizes opcode = new int[nnodes]; data = new double[nnodes]; parent = new int[nnodes]; // Get array data model.GetGenConstrNL(genc, out resvar, out nnodes, opcode, data, parent); }
Dim resvar As GRBVar Dim nnodes As Integer Dim opcode As Integer() Dim data As Double() Dim parent As Integer() ' Retrieve general constraint type Dim type as Integer = genc.Get(GRB.IntAttr.GenConstrType) If type = GRB.GENCONSTR_NL Then ' Get number of nodes model.GetGenConstrNL(genc, resvar, nnodes, Nothing, Nothing, Nothing) ' Initialize correct array sizes opcode = New Integer(nnodes) data = New Double(nnodes) parent = New Integer(nnodes) ' Get array data model.GetGenConstrNL(genc, resvar, nnodes, opcode, data, parent) End If
- void GetGenConstrIndicator(GRBGenConstr genc, out GRBVar binvar, out int binval, out GRBLinExpr expr, out char sense, out double rhs)#
Retrieve the data associated with a general constraint of type INDICATOR. Calling this method for a general constraint of a different type leads to an exception. You can query the GenConstrType attribute to determine the type of the general constraint.
See also
AddGenConstrIndicator
for a description of the semantics of this general constraint type.- Parameters:
genc – The general constraint object.
binvar – Stores the binary indicator variable of the constraint.
binval – Stores the value that the indicator variable has to take in order to trigger the linear constraint.
expr – Stores the left-hand side expression of the linear constraint that is triggered by the indicator.
sense – Stores the sense for the linear constraint. Options are
GRB.LESS_EQUAL
,GRB.EQUAL
, orGRB.GREATER_EQUAL
.rhs – Stores the right-hand side value for the linear constraint.
- Example:
GRBVar binvar; int binval; GRBLinExpr expr; char sense; double rhs; // Retrieve general constraint type int type = genc.Get(GRB.IntAttr.GenConstrType); if (type == GRB.GENCONSTR_INDICATOR) { // Retrieve data for given indicator constraint model.GetGenConstrIndicator(genc, out binvar, out binval, out expr, out sense, out rhs); }
Dim binvar As GRBVar Dim binval As Integer Dim expr As GRBLinExpr Dim sense As Char Dim rhs As Double ' Retrieve general constraint type Dim type as Integer = genc.Get(GRB.IntAttr.GenConstrType) If type = GRB.GENCONSTR_INDICATOR Then ' Retrieve data for given indicator constraint model.GetGenConstrIndicator(genc, binvar, binval, expr, sense, rhs) End If
- void GetGenConstrPWL(GRBGenConstr genc, out GRBVar xvar, out GRBVar yvar, out int npts, double[] xpts, double[] ypts)#
Retrieve the data associated with a general constraint of type PWL. Calling this method for a general constraint of a different type leads to an exception. You can query the GenConstrType attribute to determine the type of the general constraint.
Typical usage is to call this routine twice. In the first call, you specify the requested general constraint, with a
null
value for thexpts
andypts
arguments. The routine returns the length for thexpts
andypts
arrays innpts
. That allows you to make certain that thexpts
andypts
arrays are of sufficient size to hold the result of the second call.See also
AddGenConstrPWL
for a description of the semantics of this general constraint type.Any of the following arguments can be
null
.- Parameters:
genc – The general constraint object.
xvar – Store the \(x\) variable.
yvar – Store the \(y\) variable.
npts – Store the number of points that define the piecewise-linear function.
xpts – The \(x\) values for the points that define the piecewise-linear function.
ypts – The \(y\) values for the points that define the piecewise-linear function.
- Example:
GRBVar xvar; GRBVar yvar; int npts; double[] xpts; double[] ypts; // Retrieve general constraint type int type = genc.Get(GRB.IntAttr.GenConstrType); if (type == GRB.GENCONSTR_PWL) { // Get number of points model.GetGenConstrPWL(genc, out xvar, out yvar, out npts, null, null); // Initialize correct array sizes xpts = new double[npts]; ypts = new double[npts]; // Retrieve data for given PWL constraint model.GetGenConstrPWL(genc, out xvar, out yvar, out npts, xpts, ypts); }
Dim xvar As GRBVar Dim yvar As GRBVar Dim npts As Integer Dim xpts As Double() Dim ypts As Double() ' Retrieve general constraint type Dim type as Integer = genc.Get(GRB.IntAttr.GenConstrType) If type = GRB.GENCONSTR_PWL Then ' Get number of points model.GetGenConstrPWL(genc, xvar, yvar, npts, Nothing, Nothing) ' Initialize correct array sizes xpts = New double(npts) ypts = New double(npts) ' Retrieve data for given PWL constraint model.GetGenConstrPWL(genc, xvar, yvar, npts, xpts, ypts) End If
- void GetGenConstrPoly(GRBGenConstr genc, out GRBVar xvar, out GRBVar yvar, out int plen, double[] p)#
Retrieve the data associated with a general constraint of type POLY. Calling this method for a general constraint of a different type leads to an exception. You can query the GenConstrType attribute to determine the type of the general constraint.
Typical usage is to call this routine twice. In the first call, you specify the requested general constraint, with a
null
value for thep
argument. The routine returns the length of thep
array inplen
. That allows you to make certain that thep
array is of sufficient size to hold the result of the second call.See also
AddGenConstrPoly
for a description of the semantics of this general constraint type.Any of the following arguments can be
null
.- Parameters:
genc – The general constraint object.
xvar – Store the \(x\) variable.
yvar – Store the \(y\) variable.
plen – Store the array length for p. If \(x^d\) is the highest power term, then \(d+1\) will be returned.
p – The coefficients for polynomial function.
- Example:
GRBVar xvar; GRBVar yvar; int plen; double[] p; // Retrieve general constraint type int type = genc.Get(GRB.IntAttr.GenConstrType); if (type == GRB.GENCONSTR_POLY) { // Get number of coefficients model.GetGenConstrPoly(genc, out xvar, out yvar, out plen, null); // Initialize correct array size p = new double[plen]; // Retrieve data for given poly constraint model.GetGenConstrPoly(genc, out xvar, out yvar, out plen, p); }
Dim xvar As GRBVar Dim yvar As GRBVar Dim plen As Integer Dim p As Double() ' Retrieve general constraint type Dim type as Integer = genc.Get(GRB.IntAttr.GenConstrType) If type = GRB.GENCONSTR_POLY Then ' Get number of coefficients model.GetGenConstrPoly(genc, xvar, yvar, plen, Nothing) ' Initialize correct array size p = New Double(plen) ' Retrieve data for given poly constraint model.GetGenConstrPoly(genc, xvar, yvar, plen , p) End If
- void GetGenConstrExp(GRBGenConstr genc, out GRBVar xvar, out GRBVar yvar)#
Retrieve the data associated with a general constraint of type EXP. Calling this method for a general constraint of a different type leads to an exception. You can query the GenConstrType attribute to determine the type of the general constraint.
See also
AddGenConstrExp
for a description of the semantics of this general constraint type.Any of the following arguments can be
null
.- Parameters:
genc – The general constraint object.
xvar – Store the \(x\) variable.
yvar – Store the \(y\) variable.
- Example:
GRBVar xvar; GRBVar yvar; // Retrieve general constraint type int type = genc.Get(GRB.IntAttr.GenConstrType); if (type == GRB.GENCONSTR_EXP) { // Retrieve data for given exp constraint model.GetGenConstrExp(genc, out xvar, out yvar); }
Dim xvar As GRBVar Dim yvar As GRBVar ' Retrieve general constraint type Dim type as Integer = genc.Get(GRB.IntAttr.GenConstrType) If type = GRB.GENCONSTR_EXP Then ' Retrieve data for given exp constraint model.GetGenConstrExp(genc, xvar, yvar) End If
- void GetGenConstrExpA(GRBGenConstr genc, out GRBVar xvar, out GRBVar yvar, out double a)#
Retrieve the data associated with a general constraint of type EXPA. Calling this method for a general constraint of a different type leads to an exception. You can query the GenConstrType attribute to determine the type of the general constraint.
See also
AddGenConstrExpA
for a description of the semantics of this general constraint type.Any of the following arguments can be
null
.- Parameters:
genc – The general constraint object.
xvar – Store the \(x\) variable.
yvar – Store the \(y\) variable.
a – Store the base of the function.
- Example:
GRBVar xvar; GRBVar yvar; double a; // Retrieve general constraint type int type = genc.Get(GRB.IntAttr.GenConstrType); if (type == GRB.GENCONSTR_EXPA) { // Retrieve data for given exp_a constraint model.GetGenConstrExpA(genc, out xvar, out yvar, out a); }
Dim xvar As GRBVar Dim yvar As GRBVar Dim a As Double ' Retrieve general constraint type Dim type as Integer = genc.Get(GRB.IntAttr.GenConstrType) If type = GRB.GENCONSTR_EXPA Then ' Retrieve data for given exp_a constraint model.GetGenConstrExpA(genc, xvar, yvar, a) End If
- void GetGenConstrLog(GRBGenConstr genc, out GRBVar xvar, out GRBVar yvar)#
Retrieve the data associated with a general constraint of type LOG. Calling this method for a general constraint of a different type leads to an exception. You can query the GenConstrType attribute to determine the type of the general constraint.
See also
AddGenConstrLog
for a description of the semantics of this general constraint type.Any of the following arguments can be
null
.- Parameters:
genc – The general constraint object.
xvar – Store the \(x\) variable.
yvar – Store the \(y\) variable.
- Example:
GRBVar xvar; GRBVar yvar; // Retrieve general constraint type int type = genc.Get(GRB.IntAttr.GenConstrType); if (type == GRB.GENCONSTR_LOG) { // Retrieve data for given log constraint model.GetGenConstrLog(genc, out xvar, out yvar); }
Dim xvar As GRBVar Dim yvar As GRBVar ' Retrieve general constraint type Dim type as Integer = genc.Get(GRB.IntAttr.GenConstrType) If type = GRB.GENCONSTR_LOG Then ' Retrieve data for given log constraint model.GetGenConstrLog(genc, xvar, yvar) End If
- void GetGenConstrLogA(GRBGenConstr genc, out GRBVar xvar, out GRBVar yvar, out double a)#
Retrieve the data associated with a general constraint of type LOGA. Calling this method for a general constraint of a different type leads to an exception. You can query the GenConstrType attribute to determine the type of the general constraint.
See also
AddGenConstrLogA
for a description of the semantics of this general constraint type.Any of the following arguments can be
null
.- Parameters:
genc – The general constraint object.
xvar – Store the \(x\) variable.
yvar – Store the \(y\) variable.
a – Store the base of the function.
- Example:
GRBVar xvar; GRBVar yvar; double a; // Retrieve general constraint type int type = genc.Get(GRB.IntAttr.GenConstrType); if (type == GRB.GENCONSTR_LOGA) { // Retrieve data for given log_a constraint model.GetGenConstrLogA(genc, out xvar, out yvar, out a); }
Dim xvar As GRBVar Dim yvar As GRBVar Dim a As Double ' Retrieve general constraint type Dim type as Integer = genc.Get(GRB.IntAttr.GenConstrType) If type = GRB.GENCONSTR_LOGA Then ' Retrieve data for given log_a constraint model.GetGenConstrLogA(genc, xvar, yvar, a) End If
- void GetGenConstrLogistic(GRBGenConstr genc, out GRBVar xvar, out GRBVar yvar)#
Retrieve the data associated with a general constraint of type LOGISTIC. Calling this method for a general constraint of a different type leads to an exception. You can query the GenConstrType attribute to determine the type of the general constraint.
See also
AddGenConstrLogistic
for a description of the semantics of this general constraint type.Any of the following arguments can be
null
.- Parameters:
genc – The general constraint object.
xvar – Store the \(x\) variable.
yvar – Store the \(y\) variable.
- Example:
GRBVar xvar; GRBVar yvar; // Retrieve general constraint type int type = genc.Get(GRB.IntAttr.GenConstrType); if (type == GRB.GENCONSTR_LOGISTIC) { // Retrieve data for given logistic constraint model.GetGenConstrLogistic(genc, out xvar, out yvar); }
Dim xvar As GRBVar Dim yvar As GRBVar ' Retrieve general constraint type Dim type as Integer = genc.Get(GRB.IntAttr.GenConstrType) If type = GRB.GENCONSTR_LOGISTIC Then ' Retrieve data for given logistic constraint model.GetGenConstrLogistic(genc, xvar, yvar) End If
- void GetGenConstrPow(GRBGenConstr genc, out GRBVar xvar, out GRBVar yvar, out double a)#
Retrieve the data associated with a general constraint of type POW. Calling this method for a general constraint of a different type leads to an exception. You can query the GenConstrType attribute to determine the type of the general constraint.
See also
AddGenConstrPow
for a description of the semantics of this general constraint type.Any of the following arguments can be
null
.- Parameters:
genc – The general constraint object.
xvar – Store the \(x\) variable.
yvar – Store the \(y\) variable.
a – Store the power of the function.
- Example:
GRBVar xvar; GRBVar yvar; double a; // Retrieve general constraint type int type = genc.Get(GRB.IntAttr.GenConstrType); if (type == GRB.GENCONSTR_POW) { // Retrieve data for given power constraint model.GetGenConstrPow(genc, out xvar, out yvar, out a); }
Dim xvar As GRBVar Dim yvar As GRBVar Dim a As Double ' Retrieve general constraint type Dim type as Integer = genc.Get(GRB.IntAttr.GenConstrType) If type = GRB.GENCONSTR_POW Then ' Retrieve data for given power constraint model.GetGenConstrPow(genc, xvar, yvar, a) End If
- void GetGenConstrSin(GRBGenConstr genc, out GRBVar xvar, out GRBVar yvar)#
Retrieve the data associated with a general constraint of type SIN. Calling this method for a general constraint of a different type leads to an exception. You can query the GenConstrType attribute to determine the type of the general constraint.
See also
AddGenConstrSin
for a description of the semantics of this general constraint type.Any of the following arguments can be
null
.- Parameters:
genc – The general constraint object.
xvar – Store the \(x\) variable.
yvar – Store the \(y\) variable.
- Example:
GRBVar xvar; GRBVar yvar; // Retrieve general constraint type int type = genc.Get(GRB.IntAttr.GenConstrType); if (type == GRB.GENCONSTR_SIN) { // Retrieve data for given sin constraint model.GetGenConstrSin(genc, out xvar, out yvar); }
Dim xvar As GRBVar Dim yvar As GRBVar ' Retrieve general constraint type Dim type as Integer = genc.Get(GRB.IntAttr.GenConstrType) If type = GRB.GENCONSTR_SIN Then ' Retrieve data for given sin constraint model.GetGenConstrSin(genc, xvar, yvar) End If
- void GetGenConstrCos(GRBGenConstr genc, out GRBVar xvar, out GRBVar yvar)#
Retrieve the data associated with a general constraint of type COS. Calling this method for a general constraint of a different type leads to an exception. You can query the GenConstrType attribute to determine the type of the general constraint.
See also
AddGenConstrCos
for a description of the semantics of this general constraint type.Any of the following arguments can be
null
.- Parameters:
genc – The general constraint object.
xvar – Store the \(x\) variable.
yvar – Store the \(y\) variable.
- Example:
GRBVar xvar; GRBVar yvar; // Retrieve general constraint type int type = genc.Get(GRB.IntAttr.GenConstrType); if (type == GRB.GENCONSTR_COS) { // Retrieve data for given cos constraint model.GetGenConstrCos(genc, out xvar, out yvar); }
Dim xvar As GRBVar Dim yvar As GRBVar ' Retrieve general constraint type Dim type as Integer = genc.Get(GRB.IntAttr.GenConstrType) If type = GRB.GENCONSTR_COS Then ' Retrieve data for given cos constraint model.GetGenConstrCos(genc, xvar, yvar) End If
- void GetGenConstrTan(GRBGenConstr genc, out GRBVar xvar, out GRBVar yvar)#
Retrieve the data associated with a general constraint of type TAN. Calling this method for a general constraint of a different type leads to an exception. You can query the GenConstrType attribute to determine the type of the general constraint.
See also
AddGenConstrTan
for a description of the semantics of this general constraint type.Any of the following arguments can be
null
.- Parameters:
genc – The general constraint object.
xvar – Store the \(x\) variable.
yvar – Store the \(y\) variable.
- Example:
GRBVar xvar; GRBVar yvar; // Retrieve general constraint type int type = genc.Get(GRB.IntAttr.GenConstrType); if (type == GRB.GENCONSTR_TAN) { // Retrieve data for given tan constraint model.GetGenConstrTan(genc, out xvar, out yvar); }
Dim xvar As GRBVar Dim yvar As GRBVar ' Retrieve general constraint type Dim type as Integer = genc.Get(GRB.IntAttr.GenConstrType) If type = GRB.GENCONSTR_TAN Then ' Retrieve data for given tan constraint model.GetGenConstrTan(genc, xvar, yvar) End If
- GRBGenConstr[] GetGenConstrs()#
Retrieve an array of all general constraints in the model.
- Returns:
All general constraints in the model.
- Example:
GRBGenConstr[] constrs = model.GetGenConstrs();
Dim constrs as GRBGenConstr() = model.GetGenConstrs()
- string GetJSONSolution()#
After a call to
Optimize
, this method returns the resulting solution and related model attributes as a JSON string. Please refer to the JSON solution format section for details.- Returns:
A JSON string.
- Example:
string solution = model.GetJSONSolution();
Dim solutions As String = model.GetJSONSolution()
- GRBEnv GetMultiobjEnv(int index)#
Create/retrieve a multi-objective environment for the optimization pass with the given index. This environment enables fine-grained control over the multi-objective optimization process. Specifically, by changing parameters on this environment, you modify the behavior of the optimization that occurs during the corresponding pass of the multi-objective optimization.
Each multi-objective environment starts with a copy of the current model environment.
Please refer to the discussion of Multiple Objectives for information on how to specify multiple objective functions and control the trade-off between them.
Please refer to the discussion on Combining Blended and Hierarchical Objectives for information on the optimization passes to solve multi-objective models.
Use
DiscardMultiobjEnvs
to discard multi-objective environments and return to standard behavior.- Parameters:
index – The optimization pass index, starting from 0.
- Returns:
The multi-objective environment for that optimization pass when solving the model.
- Example:
env0 = model.GetMultiobjEnv(0); env1 = model.GetMultiobjEnv(1); env0.Set(GRB.IntParam.Method, 0); env1.Set(GRB.IntParam.Method, 1); model.Optimize(); model.DiscardMultiobjEnvs();
env0 = model.GetMultiobjEnv(0) env1 = model.GetMultiobjEnv(1) env0.Set(GRB.IntParam.Method, 0) env1.Set(GRB.IntParam.Method, 1) model.Optimize() model.DiscardMultiobjEnvs()
- GRBExpr GetObjective()#
Retrieve the optimization objective.
Note that the constant and linear portions of the objective can also be retrieved using the ObjCon and Obj attributes.
- Returns:
The model objective.
- Example:
// Get linear objective expression GRBLinExpr obj = model.GetObjective(); double objval = obj.Value;
' Get linear objective expression Dim obj As GRBLinExpr = model.GetObjective() Dim objVal As Double = obj.Value
- GRBLinExpr GetObjective(int index)#
Retrieve an alternative optimization objective. Alternative objectives will always be linear. You can also use this routine to retrieve the primary objective (using
index
= 0), but you will get an exception if the primary objective contains quadratic terms.Please refer to the discussion of Multiple Objectives for more information on the use of alternative objectives.
Note that alternative objectives can also be retrieved using the ObjNCon and ObjN attributes.
- Parameters:
index – The index for the requested alternative objective.
- Returns:
The requested alternative objective.
- Example:
// Get second linear objective GRBLinExpr obj = model.GetObjective(1); double objval = obj.Value;
' Get linear objective expression Dim obj As GRBLinExpr = model.GetObjective(1) Dim objVal As Double = obj.Value
- int GetPWLObj(GRBVar var, double[] x, double[] y)#
Retrieve the piecewise-linear objective function for a variable. The return value gives the number of points that define the function, and the \(x\) and \(y\) arguments give the coordinates of the points, respectively. The \(x\) and \(y\) arguments must be large enough to hold the result. Call this method with
null
values for \(x\) and \(y\) if you just want the number of points.Refer to this discussion for additional information on what the values in \(x\) and \(y\) mean.
- Parameters:
var – The variable whose objective function is being retrieved.
x – The \(x\) values for the points that define the piecewise-linear function. These will always be in non-decreasing order.
y – The \(y\) values for the points that define the piecewise-linear function.
- Returns:
The number of points that define the piecewise-linear objective function.
- Example:
// Get PWL objective data int npts = model.GetPWLObj(var, null, null); double[] x = new double[npts]; double[] y = new double[npts]; model.GetPWLObj(var, x, y);
' Get PWL objective data Dim npts As Integer = model.GetPWLObj(var, Nothing, Nothing) Dim x as Double() = New Double(npts) Dim y as Double() = New Double(npts) model.GetPWLObj(var, x, y)
- GRBQConstr[] GetQConstrs()#
Retrieve an array of all quadratic constraints in the model.
- Returns:
All quadratic constraints in the model.
- Example:
GRBQConstr[] constrs = model.GetQConstrs();
Dim constrs As GRBQConstr() = model.GetQConstrs()
- GRBQuadExpr GetQCRow(GRBQConstr qc)#
Retrieve the left-hand side expression for a quadratic constraint. The result is returned as a
GRBQuadExpr
object.- Parameters:
qc – The quadratic constraint of interest.
- Returns:
A
GRBQuadExpr
object that captures the left-hand side of the quadratic constraint.- Example:
// Get quadratic LHS expression of first quadratic constraint GRBQConstr[] constrs = model.GetQConstrs(); GRBQuadExpr qexpr = model.GetQCRow(constrs[0]);
' Get quadratic LHS expression of first quadratic constraint Dim constrs As GRBQConstr() = model.GetQConstrs() Dim qexpr As GRBQuadExpr = model.GetQCRow(constrs(0))
- GRBLinExpr GetRow(GRBConstr constr)#
Retrieve a list of variables that participate in a constraint, and the associated coefficients. The result is returned as a
GRBLinExpr
object.- Parameters:
constr – The constraint of interest. A
GRBConstr
object, typically obtained fromAddConstr
orGetConstrs
.- Returns:
A
GRBLinExpr
object that captures the set of variables that participate in the constraint.- Example:
// Get linear LHS expression of first linear constraint GRBConstr[] constrs = model.GetConstrs(); GRBLinExpr lexpr = model.GetRow(constrs[0]);
' Get linear LHS expression of first linear constraint Dim constrs As GRBConstr() = model.GetConstrs() Dim lexpr As GRBLinExpr = model.GetRow(constrs(0))
- int GetSOS(GRBSOS sos, GRBVar[] vars, double[] weights, int[] type)#
Retrieve the list of variables that participate in an SOS constraint, and the associated coefficients. The return value is the length of this list. Note that the argument arrays must be long enough to accommodate the result. Call the method with
null
array arguments to determine the appropriate array lengths.- Parameters:
sos – The SOS set of interest.
vars – A list of variables that participate in
sos
. Can benull
.weights – The SOS weights for each participating variable. Can be
null
.type – The type of the SOS set (either
GRB.SOS_TYPE1
orGRB.SOS_TYPE2
) is returned intype[0]
.
- Returns:
The number of entries placed in the output arrays. Note that you should consult the return value to determine the length of the result; the arrays sizes won’t necessarily match the result size.
- Example:
GRBSOS[] constrs = model.GetSOSs(); // Get data of first SOS constraint int len = model.GetSOS(constrs[0], null, null, null); GRBVar[] vars = new GRBVar[len]; double[] weights = new double[len]; int[] type = new int[len]; model.GetSOS(constrs[0], vars, weights, type);
Dim constrs As GRBSOS() = model.GetSOSs() ' Get data of first SOS constraint Dim len As Integer = model.GetSOS(constrs(0), Nothing, Nothing, Nothing) Dim vars As GRBVar() = New GRBVarlen Dim weights As Double() = New Double(len) Dim type As Integer() = New Integer(len) model.GetSOS(constrs(0), vars, weights, type)
- GRBSOS[] GetSOSs()#
Retrieve an array of all SOS constraints in the model.
- Returns:
All SOS constraints in the model.
- Example:
GRBSOS[] constrs = model.GetSOSs();
Dim constrs As GRBSOS() = model.GetSOSs()
- void GetTuneResult(int n)#
Use this method to retrieve the results of a previous
Tune
call. Calling this method with argumentn
causes tuned parameter setn
to be copied into the model. Parameter sets are stored in order of decreasing quality, with parameter set 0 being the best. The number of available sets is stored in attribute TuneResultCount.Once you have retrieved a tuning result, you can call
optimize
to use these parameter settings to optimize the model, orwrite
to write the changed parameters to a.prm
file.Please refer to the parameter tuning section for details on the tuning tool.
- Parameters:
n – The index of the tuning result to retrieve. The best result is available as index 0. The number of stored results is available in attribute TuneResultCount.
- Example:
model.Tune(); // Get best tuning result model.GetTuneResult(0); // Optimize model using the best found parameter set model.Optimize();
model.Tune() ' Get best tuning result model.GetTuneResult(0) ' Optimize model using the best found parameter set model.Optimize()
- GRBVar GetVarByName(string name)#
Retrieve a variable from its name. If multiple variable have the same name, this method chooses one arbitrarily.
- Parameters:
name – The name of the desired variable.
- Returns:
The requested variable.
- Example:
// Get variable named "var1" GRBVar var = model.GetVarByName("var1");
' Get variable named "var1" Dim var As GRBVar = model.GetVarByName("var1")
- GRBVar[] GetVars()#
Retrieve an array of all variables in the model.
- Returns:
All variables in the model.
- Example:
GRBVar[] vars = model.GetVars();
Dim vars As GRBVar() = model.GetVars()
- void Optimize()#
Optimize the model. The algorithm used for the optimization depends on the model type (simplex or barrier for a continuous model; branch-and-cut for a MIP model). Upon successful completion, this method will populate the solution related attributes of the model. See the Attributes section for more information on attributes.
Please consult this section for a discussion of some of the practical issues associated with solving a precisely defined mathematical model using finite-precision floating-point arithmetic.
Note that this method will process all pending model modifications.
- Example:
model.Optimize();
model.Optimize()
- void OptimizeAsync()#
Optimize a model asynchronously. This routine returns immediately. Your program can perform other computations while optimization proceeds in the background. To check the state of the asynchronous optimization, query the Status attribute for the model. A value of
IN_PROGRESS
indicates that the optimization has not yet completed. When you are done with your foreground tasks, you must callSync
to sync your foreground program with the asynchronous optimization task.Note that the set of Gurobi calls that you are allowed to make while optimization is running in the background is severely limited. Specifically, you can only perform attribute queries, and only for a few attributes (listed below). Any other calls on the running model, or on any other models that were built within the same Gurobi environment, will fail with error code OPTIMIZATION_IN_PROGRESS.
Note that there are no such restrictions on models built in other environments. Thus, for example, you could create multiple environments, and then have a single foreground program launch multiple simultaneous asynchronous optimizations, each in its own environment.
As already noted, you are allowed to query the value of the Status attribute while an asynchronous optimization is in progress. The other attributes that can be queried are: ObjVal, ObjBound, IterCount, NodeCount, and BarIterCount. In each case, the returned value reflects progress in the optimization to that point. Any attempt to query the value of an attribute not on this list will return an OPTIMIZATION_IN_PROGRESS error.
- Example:
// Start asynchronous optimization model.OptimizeAsync(); // Poll the status while optimization is in progress while (model.Get(GRB.IntAttr.Status) == GRB.Status.INPROGRESS) { Thread.Sleep(100); // Sleep for 100 ms Console.WriteLine($"ObjVal={model.Get(GRB.DoubleAttr.ObjVal)} ObjBound={model.Get(GRB.DoubleAttr.ObjBound)}"); } // Synchronize model model.Sync(); // Query solution and process results // ...
' Start asynchronous optimization model.OptimizeAsync() ' Poll the status while optimization is in progress While model.Get(GRB.IntAttr.Status) = GRB.Status.INPROGRESS Thread.Sleep(100) ' Sleep for 100 ms Console.WriteLine("ObjVal=" & model.Get(GRB.DoubleAttr.ObjVal) & " ObjBound=" & model.Get(GRB.DoubleAttr.ObjBound)) End While ' Synchronize model model.Sync() ' Query solution and process results ' ...
- string OptimizeBatch()#
Submit a new batch request to the Cluster Manager. Returns the BatchID (a string), which uniquely identifies the job in the Cluster Manager and can be used to query the status of this request (from this program or from any other). Once the request has completed, the BatchID can also be used to retrieve the associated solution. To submit a batch request, you must tag at least one element of the model by setting one of the VTag, CTag or QCTag attributes. For more details on batch optimization, please refer to the Batch Optimization section.
Note that this routine will process all pending model modifications.
- Example:
// Submit batch request string batchID = model.OptimizeBatch();
' Submit batch request Dim batchID As String = model.OptimizeBatch()
- GRBModel Presolve()#
Perform presolve on a model.
Please note that the presolved model computed by this function may be different from the presolved model computed when optimizing the model.
- Returns:
Presolved version of original model.
- Example:
GRBModel presolved = model.Presolve();
Dim presolved As GRBModel = model.Presolve()
- void Read(string filename)#
This method is the general entry point for importing data from a file into a model. It can be used to read basis files for continuous models, start vectors for MIP models, variable hints for MIP models, branching priorities for MIP models, or parameter settings. The type of data read is determined by the file suffix. File formats are described in the File Format section.
Note that reading a file does not process all pending model modifications. These modifications can be processed by calling
GRBModel.Update
.Note also that this is not the method to use if you want to read a new model from a file. For that, use the
GRBModel constructor
. One variant of the constructor takes the name of the file that contains the new model as its argument.- Parameters:
filename – Name of the file to read. The suffix on the file must be either
.bas
(for an LP basis),.mst
or.sol
(for a MIP start),.hnt
(for MIP hints),.ord
(for a priority order),.attr
(for a collection of attribute settings), or.prm
(for a parameter file). The suffix may optionally be followed by.zip
,.gz
,.bz2
,.7z
or.xz
.- Example:
model.Read("myModel.mps");
model.Read("myModel.mps")
- void Remove(GRBConstr constr)#
Remove a constraint from the model. Note that, due to our lazy update approach, the change won’t actually take effect until you update the model (using
GRBModel.Update
), optimize the model (usingGRBModel.Optimize
), or write the model to disk (usingGRBModel.Write
).- Parameters:
constr – The constraint to remove.
- Example:
GRBConstr[] constrs = model.GetConstrs(); // Remove first linear constraint model.Remove(constrs[0]);
Dim constrs As GRBConstr() = model.GetConstrs() ' Remove first linear constraint model.Remove(constrs(0))
- void Remove(GRBGenConstr genconstr)#
Remove a general constraint from the model. Note that, due to our lazy update approach, the change won’t actually take effect until you update the model (using
GRBModel.Update
), optimize the model (usingGRBModel.Optimize
), or write the model to disk (usingGRBModel.Write
).- Parameters:
genconstr – The general constraint to remove.
- Example:
GRBGenConstr[] constrs = model.GetGenConstrs(); // Remove first general constraint model.Remove(constrs[0]);
Dim constrs As GRBGenConstr() = model.GetGenConstrs() ' Remove first general constraint model.Remove(constrs(0))
- void Remove(GRBQConstr qconstr)#
Remove a quadratic constraint from the model. Note that, due to our lazy update approach, the change won’t actually take effect until you update the model (using
GRBModel.Update
), optimize the model (usingGRBModel.Optimize
), or write the model to disk (usingGRBModel.Write
).- Parameters:
qconstr – The constraint to remove.
- Example:
GRBQConstr[] constrs = model.GetQConstrs(); // Remove first quadratic constraint model.Remove(constrs[0]);
Dim constrs As GRBQConstr = model.GetQConstrs() ' Remove first quadratic constraint model.Remove(constrs(0))
- void Remove(GRBSOS sos)#
Remove an SOS constraint from the model. Note that, due to our lazy update approach, the change won’t actually take effect until you update the model (using
GRBModel.Update
), optimize the model (usingGRBModel.Optimize
), or write the model to disk (usingGRBModel.Write
).- Parameters:
sos – The SOS constraint to remove.
- Example:
GRBSOS[] constrs = model.GetSOSs(); // Remove first SOS constraint model.Remove(constrs[0]);
Dim constrs As GRBSOS() = model.GetSOSs() ' Remove first SOS constraint model.Remove(constrs(0))
- void Remove(GRBVar var)#
Remove a variable from the model. Note that, due to our lazy update approach, the change won’t actually take effect until you update the model (using
GRBModel.Update
), optimize the model (usingGRBModel.Optimize
), or write the model to disk (usingGRBModel.Write
).- Parameters:
var – The variable to remove.
- Example:
GRBVar[] vars = model.GetVars(); // Remove first variable model.Remove(vars[0]);
Dim vars As GRBVar() = model.GetVars() ' Remove first variable model.Remove(vars(0))
- void Reset()#
Reset the model to an unsolved state, discarding any previously computed solution information.
- Example:
model.Reset();
model.Reset()
- void Reset(int clearall)#
Reset the model to an unsolved state, discarding any previously computed solution information.
- Parameters:
clearall – A value of 1 discards additional information that affects the solution process but not the actual model (currently MIP starts, variable hints, branching priorities, lazy flags, and partition information). Pass 0 to just discard the solution.
- Example:
model.Reset(1);
model.Reset(1)
- void SetCallback(GRBCallback cb)#
Set the callback object for a model. The
Callback()
method on this object will be called periodically from the Gurobi solver. You will have the opportunity to obtain more detailed information about the state of the optimization from this callback. See the documentation forGRBCallback
for additional information.Note that a model can only have a single callback method, so this call will replace an existing callback. To disable a previously set callback, call this method with a
null
argument.- Example:
class MyCallback : GRBCallback { // ... } // ... MyCallback CB = new MyCallback(); // ... model.SetCallback(CB);
class MyCallback Inherits GRBCallback ' ... ' ... model.SetCallback(New CB())
- void Set(GRB.DoubleParam param, double newvalue)#
Set the value of a double-valued parameter.
The difference between setting a parameter on a model and setting it on an environment (i.e., through
GRBEnv.Set
) is that the former modifies the parameter for a single model, while the latter modifies the parameter for every model that is subsequently built using that environment (and leaves the parameter unchanged for models that were previously built using that environment).- Parame