Quality Attributes#
These are solution quality attributes. They are associated with the
overall model. You should use one of the various get
routines to
retrieve the value of an attribute. These are described at the beginning
of this section. For the object-oriented
interfaces, quality attributes are retrieved by invoking the get
method on a constraint object. For attributes that can be modified
directly by the user, you can use one of the various set
methods.
Attempting to query an attribute that is not available will produce an error. In C, the attribute query routine will return a DATA_NOT_AVAILABLE error code. The object-oriented interfaces will throw an exception.
MaxVio#
Type:
double
Modifiable:
No
Maximum of all (unscaled) violations that apply to model type.
For examples of how to query or modify attributes, refer to our Attribute Examples.
BoundVio#
Type:
double
Modifiable:
No
Maximum (unscaled) bound violation.
Available for all model types.
For examples of how to query or modify attributes, refer to our Attribute Examples.
BoundSVio#
Type:
double
Modifiable:
No
Maximum (scaled) bound violation.
Only available for continuous models.
For examples of how to query or modify attributes, refer to our Attribute Examples.
BoundVioIndex#
Type:
int
Modifiable:
No
Index of variable with the largest (unscaled) bound violation.
Available for all model types.
For examples of how to query or modify attributes, refer to our Attribute Examples.
BoundSVioIndex#
Type:
int
Modifiable:
No
Index of variable with the largest (scaled) bound violation.
Only available for continuous models.
For examples of how to query or modify attributes, refer to our Attribute Examples.
BoundVioSum#
Type:
double
Modifiable:
No
Sum of (unscaled) bound violations.
Available for all model types.
For examples of how to query or modify attributes, refer to our Attribute Examples.
BoundSVioSum#
Type:
double
Modifiable:
No
Sum of (scaled) bound violations.
Only available for continuous models.
For examples of how to query or modify attributes, refer to our Attribute Examples.
ConstrVio#
Type:
double
Modifiable:
No
Reporting constraint violations for the simplex solver is actually more
complex than it may appear, due to the treatment of slacks on linear
inequality constraints. The simplex solver introduces explicit
non-negative slack variables inside the algorithm. Thus, for example,
\(a^Tx \le b\) becomes \(a^Tx + s = b\). In this formulation,
constraint errors can show up in two places: (i) as bound violations on
the computed slack variable values, and (ii) as differences between
\(a^Tx + s\) and \(b\). We report the former as ConstrVio
and the latter as ConstrResidual.
For MIP models, the maximum violation of the constraints, including
linear, quadratic, SOS and general constraints, is reported in
ConstrVio
.
Available for all model types.
For examples of how to query or modify attributes, refer to our Attribute Examples.
ConstrSVio#
Type:
double
Modifiable:
No
Maximum (scaled) slack bound violation.
Only available for continuous models.
For examples of how to query or modify attributes, refer to our Attribute Examples.
ConstrVioIndex#
Type:
int
Modifiable:
No
Index of linear constraint with the largest (unscaled) slack bound violation for continuous linear models solved by simplex.
For MIP or other situations, it is for all the constraints. The constraint order is linear, quadratic, SOS and general. Assume there are \(l\) linear, \(q\) quadratic, \(s\) SOS and \(g\) general constraints and the index \(i\) is between \(l+q+s\) and \(l+q+s+g\), then the general constraint with index \(i-l-q-s\) has the biggest violation.
Available for all model types.
For examples of how to query or modify attributes, refer to our Attribute Examples.
ConstrSVioIndex#
Type:
int
Modifiable:
No
Index of linear constraint with the largest (scaled) slack bound violation.
Only available for continuous models.
For examples of how to query or modify attributes, refer to our Attribute Examples.
ConstrVioSum#
Type:
double
Modifiable:
No
Sum of (unscaled) slack bound violations.
Available for all model types.
For examples of how to query or modify attributes, refer to our Attribute Examples.
ConstrSVioSum#
Type:
double
Modifiable:
No
Sum of (scaled) slack bound violations.
Only available for continuous models.
For examples of how to query or modify attributes, refer to our Attribute Examples.
ConstrResidual#
Type:
double
Modifiable:
No
Reporting constraint violations for the simplex solver is actually more
complex than it may appear, due to the treatment of slacks on linear
inequality constraints. The simplex solver introduces explicit
non-negative slack variables inside the algorithm. Thus, for example,
\(a^Tx \le b\) becomes \(a^Tx + s = b\). In this formulation,
constraint errors can show up in two places: (i) as bound violations on
the computed slack variable values, and (ii) as differences between
\(a^Tx + s\) and \(b\). We report the former as ConstrVio
and the latter as ConstrResidual
.
Only available for continuous models. For MIP models, constraint violations are reported in ConstrVio.
For examples of how to query or modify attributes, refer to our Attribute Examples.
ConstrSResidual#
Type:
double
Modifiable:
No
Maximum (scaled) primal constraint error.
Only available for continuous models.
For examples of how to query or modify attributes, refer to our Attribute Examples.
ConstrResidualIndex#
Type:
int
Modifiable:
No
Index of linear constraint with the largest (unscaled) constraint error.
Only available for continuous models.
For examples of how to query or modify attributes, refer to our Attribute Examples.
ConstrSResidualIndex#
Type:
int
Modifiable:
No
Index of linear constraint with the largest (scaled) constraint error.
Only available for continuous models.
For examples of how to query or modify attributes, refer to our Attribute Examples.
ConstrResidualSum#
Type:
double
Modifiable:
No
Sum of (unscaled) linear constraint violations.
Only available for continuous models.
For examples of how to query or modify attributes, refer to our Attribute Examples.
ConstrSResidualSum#
Type:
double
Modifiable:
No
Sum of (scaled) linear constraint violations.
Only available for continuous models.
For examples of how to query or modify attributes, refer to our Attribute Examples.
DualVio#
Type:
double
Modifiable:
No
Reporting dual constraint violations for the simplex solver is actually
more complex than it may appear, due to the treatment of reduced costs
for bounded variables. The simplex solver introduces explicit
non-negative reduced-cost variables inside the algorithm. Thus,
\(a^Ty \ge c\) becomes \(a^Ty - z = c\) (where \(y\) is the
dual vector and \(z\) is the reduced cost). In this formulation,
errors can show up in two places: (i) as bound violations on the
computed reduced-cost variable values, and (ii) as differences between
\(a^Ty - z\) and \(c\). We report the former as DualVio
and
the latter as DualResidual.
DualVio
reports the maximum (unscaled) reduced-cost bound violation.
Only available for continuous models.
For examples of how to query or modify attributes, refer to our Attribute Examples.
DualSVio#
Type:
double
Modifiable:
No
Maximum (scaled) reduced cost violation.
Only available for continuous models.
For examples of how to query or modify attributes, refer to our Attribute Examples.
DualVioIndex#
Type:
int
Modifiable:
No
Index of variable with the largest (unscaled) reduced cost violation. Note that the result may be larger than the number of variables in the model, which indicates that a constraint slack is the variable with the largest violation. Subtract the variable count from the result to get the index of the corresponding constraint.
Only available for continuous models.
For examples of how to query or modify attributes, refer to our Attribute Examples.
DualSVioIndex#
Type:
int
Modifiable:
No
Index of variable with the largest (scaled) reduced cost violation. Note that the result may be larger than the number of variables in the model, which indicates that a constraint slack is the variable with the largest violation. Subtract the variable count from the result to get the index of the corresponding constraint.
Only available for continuous models.
For examples of how to query or modify attributes, refer to our Attribute Examples.
DualVioSum#
Type:
double
Modifiable:
No
Sum of (unscaled) reduced cost violations.
Only available for continuous models.
For examples of how to query or modify attributes, refer to our Attribute Examples.
DualSVioSum#
Type:
double
Modifiable:
No
Sum of (scaled) reduced cost violations.
Only available for continuous models.
For examples of how to query or modify attributes, refer to our Attribute Examples.
DualResidual#
Type:
double
Modifiable:
No
Reporting dual constraint violations for the simplex solver is actually
more complex than it may appear, due to the treatment of reduced costs
for bounded variables. The simplex solver introduces explicit
non-negative reduced-cost variables inside the algorithm. Thus,
\(a^Ty \ge c\) becomes \(a^Ty - z = c\) (where \(y\) is the
dual vector and \(z\) is the reduced cost). In this formulation,
errors can show up in two places: (i) as bound violations on the
computed reduced-cost variable values, and (ii) as differences between
\(a^Ty - z\) and \(c\). We report the former as DualVio and
the latter as DualResidual
.
DualResidual
reports the maximum (unscaled) dual constraint error.
Only available for continuous models.
For examples of how to query or modify attributes, refer to our Attribute Examples.
DualSResidual#
Type:
double
Modifiable:
No
Maximum (scaled) dual constraint error.
Only available for continuous models.
For examples of how to query or modify attributes, refer to our Attribute Examples.
DualResidualIndex#
Type:
int
Modifiable:
No
Index of variable with the largest (unscaled) dual constraint error.
Only available for continuous models.
For examples of how to query or modify attributes, refer to our Attribute Examples.
DualSResidualIndex#
Type:
int
Modifiable:
No
Index of variable with the largest (scaled) dual constraint error.
Only available for continuous models.
For examples of how to query or modify attributes, refer to our Attribute Examples.
DualResidualSum#
Type:
double
Modifiable:
No
Sum of (unscaled) dual constraint errors.
Only available for continuous models.
For examples of how to query or modify attributes, refer to our Attribute Examples.
DualSResidualSum#
Type:
double
Modifiable:
No
Sum of (scaled) dual constraint errors.
Only available for continuous models.
For examples of how to query or modify attributes, refer to our Attribute Examples.
ComplVio#
Type:
double
Modifiable:
No
Maximum complementarity violation. In an optimal solution, the product of the value of a variable and its reduced cost must be zero. This isn’t always strictly true for interior point solutions. This attribute returns the maximum complementarity violation for any variable.
Only available for continuous models.
For examples of how to query or modify attributes, refer to our Attribute Examples.
ComplVioIndex#
Type:
int
Modifiable:
No
Index of variable with the largest complementarity violation.
Only available for continuous models.
For examples of how to query or modify attributes, refer to our Attribute Examples.
ComplVioSum#
Type:
double
Modifiable:
No
Sum of complementarity violation.
Only available for continuous models.
For examples of how to query or modify attributes, refer to our Attribute Examples.
IntVio#
Type:
double
Modifiable:
No
A MIP solver won’t always assign strictly integral values to integer variables. This attribute returns the largest distance between the computed value of any integer variable and the nearest integer.
Only available for MIP models.
For examples of how to query or modify attributes, refer to our Attribute Examples.
IntVioIndex#
Type:
int
Modifiable:
No
Index of variable with the largest integrality violation.
Only available for MIP models.
For examples of how to query or modify attributes, refer to our Attribute Examples.
IntVioSum#
Type:
double
Modifiable:
No
Sum of integrality violations.
Only available for MIP models.
For examples of how to query or modify attributes, refer to our Attribute Examples.