# 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.