[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
## Re: [Help-glpk] [Fwd: Glpsol Changing Tolerance]

**From**: |
Andrew Makhorin |

**Subject**: |
Re: [Help-glpk] [Fwd: Glpsol Changing Tolerance] |

**Date**: |
Fri, 12 Jul 2013 16:48:55 +0400 |

>* I'm having a problem with using glpsol to solve an MIP problem using the*
>* default tolerances. Using the MIP variant of my problem glpsol find an*
>* integral optimal solution; however when I take that solution and solve*
>* the problem again with the integer variables converted to parameters the*
>* solution is vastly different. I have had this issue before with*
>* commercial solvers and have solved it by tightening the integrality*
>* tolerance to 0. Unfortunately I cannot determine a way to do this with*
>* glpsol. Any assistance would be appreciated.*
>* *
You need to change the control parameter iocp.tol_int. You cannot do it
from the command-line, however, you may patch the glpsol source code.
Take file glpk/src/glpapi21.c, find the call to glp_inopt, and add a
line above it as follows:
csa->iocp.tol_int = 1e-20;
glp_intopt(csa->prob, &csa->iocp);
Note that tol_int should be positive, i.e. zero is not allowed.