Initializing help system before first use

KEEPBASIS

Description
Simplex: This determines whether the basis should be kept when reoptimizing a problem. The choice is between using a crash basis created at the beginning of simplex or using a basis from a previous solve (if such exists). By default, this control gets (re)set automatically in various situations. By default, it will be automatically set to 1 after a solve that produced a valid basis. This will automatically warmstart a subsequent solve. Explicitly loading a starting basis will also set this control to 1. If the control is explicitly set to 0, any existing basis will be ignored for a new solve, and the Optimizer will start from an ad-hoc crash basis.
Type
Integer
Topic areas
LP, Simplex
Values
0 
Problem optimization starts from scratch, i.e., any previous basis is ignored.
1 
The previous basis should be used as a starting basis.
2 
Use the previous basis only if it is valid for the current problem (the number of basic variables must match the number of rows).
3 
Use the previous basis only if it is valid and numerically stable in the current problem.
Default value
0
Note
Some pre-LP MIP heuristics are affected by this control (since they use a starting basis if one is available).
Note
Keeping a basis can lead to less effective presolving since the Optimizer will avoid presolving operations that invalidate the given basis.
Affects routines
XPRSlpoptimize ( LPOPTIMIZE), XPRSmipoptimize ( MIPOPTIMIZE).
Category
Control

Parent Topic Control Parameters

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