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Re: [Bug-glpk] Problem to solve MIP problem
From: |
Andrew Makhorin |
Subject: |
Re: [Bug-glpk] Problem to solve MIP problem |
Date: |
Mon, 27 Oct 2008 20:18:34 +0300 |
> I have this problem:
> When I use this routine (lpx_intopt(glpkProbPtr)), my problem is solved
> normally.
> But, when I use this routine
> (glp_intopt(glpkProbPtr,&glpkParamMipPtr)), my
> problem doesn't solve the problem.
> The error message is: glp_intopt: optimal basis to initial LP relaxation not
> provided
> I don't unsderstand. None parameters are passed at glpkParamMipPtr.
> Just, I initialize glpkParamMipPtr with glp_init_iocp(&glpkParamMipPtr);
> why?
If the mip presolver is disabled (by default it is disabled),
glp_intopt expects the current basis of lp relaxation to be optimal.
To resolve the issue you should either enable the mip presolver or
call glp_simplex before a call to glp_intopt to find optimal basic
solution to the lp relaxation.