# DualResidual

Filter Content By
Version
Languages

### DualResidual

Type: double 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, becomes (where is the dual vector and 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 and . 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.