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## Re: [Help-glpk] glp_get_col_prim() problem

**From**: |
Volkan YAZICI |

**Subject**: |
Re: [Help-glpk] glp_get_col_prim() problem |

**Date**: |
Thu, 22 Apr 2010 16:01:10 +0300 |

**User-agent**: |
Gnus/5.11 (Gnus v5.11) Emacs/22.2 (gnu/linux) |

Hi,
On Thu, 22 Apr 2010, Andrew Makhorin <address@hidden> writes:
>* Most likely your instance has multiple optima, so your program finds*
>* one optimal solution while glpsol finds another. As you can see the*
>* optimal objective value is the same in both cases.*
>
>* Note that to solve mip you need to call glp_simplex (to find optimal*
>* solution to lp relaxation) and *then* call glp_intopt (to find integer*
>* optimal solution), in which case the column values should be obtained*
>* with glp_mip_col_val, not with glp_get_col_prim. It happened that for*
>* your particular instance optimal solution to lp relaxation is integer*
>* feasible and therefore integer optimal; however, in a general case*
>* glp_intopt should be used. For details please see the glpk reference*
>* manual.*
I incorporated glp_mip_col_val() and glp_intopt() into the code, and it
works like a charm. OTOH, please excuse my ignorance, but assuming all
my variables are marked as binary in CPLEX LP file, do I really need to
call glp_intopt() after glp_simplex() even if glp_get_status(lp) ==
GLP_OPT assertion holds?
Regards.