Initializing help system before first use

PRESOLVE

Description
This control determines whether presolving should be performed prior to starting the main algorithm. Presolve attempts to simplify the problem by detecting and removing redundant constraints, tightening variable bounds, etc. In some cases, infeasibility may even be determined at this stage, or the optimal solution found.
Type
Integer
Values
-1 
Presolve applied, but a problem will not be declared infeasible if primal infeasibilities are detected. The problem will be solved by the LP optimization algorithm, returning an infeasible solution, which can sometimes be helpful.
0 
Presolve not applied.
1 
Presolve applied.
2 
Presolve applied, but redundant bounds are not removed. This can sometimes increase the efficiency of the barrier algorithm.
3 
Presolve is applied, and bounds detected to be redundant are always removed.
Default value
1
Note
Memory for presolve is dynamically resized. If the Optimizer runs out of memory for presolve, an error message ( 245) is produced.

Presolve settings 2 and 3 can sometimes make the barrier solves more efficient.
Affects routines
XPRSlpoptimize ( LPOPTIMIZE), XPRSmipoptimize ( MIPOPTIMIZE).
See also
Working with Presolve, PRESOLVEOPS.

Parent Topic Control Parameters

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