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Re: [Help-glpk] help me!!!
From: |
Andrew Makhorin |
Subject: |
Re: [Help-glpk] help me!!! |
Date: |
Mon, 02 Dec 2002 18:09:20 +0300 |
>I am now working on solving the sample.c data by MIP methods and always
>get a results of "px_integer: optimal solution of LP relaxation
>required"
>
>Can anyone tell me why and how to fix it??
Before using lpx_integer you should obtain an optimal solution of LP
relaxation by means of lpx_simplex. In other word, your program should
look like follows:
...
/* create mip problem instance */
lp = lpx_create_prob();
lpx_set_class(lp, LPX_MIP);
...
/* scale the problem (optional) */
lpx_scale_prob(lp);
/* construct advanced initial basis (optional) */
lpx_adv_basis(lp);
/* find optimal solution of LP relaxation */
ret = lpx_simplex(lp);
/* make sure that the simplex method has successfully solved lp */
assert(ret == LPX_E_OK);
/* make sure that optimal solution exists */
assert(lpx_get_status(lp) == LPX_OPT);
/* try to solve mip using the branch-and-bound method */
ret = lpx_integer(lp);
...