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Re: [Help-glpk] Relaxed LP Results
From: |
Andrew Makhorin |
Subject: |
Re: [Help-glpk] Relaxed LP Results |
Date: |
Sat, 25 Aug 2007 05:27:00 +0400 |
> I'm sure I'm probably doing something wrong. Here's my code--
>
> lpx_set_class(LP, LPX_MIP);
> lpx_set_int_parm(LP, LPX_K_USECUTS, LPX_C_ALL);
> Status = lpx_intopt(LP);
> Status = lpx_mip_status(LP);
> for (int i=0;i<numcols;i++) lpx_set_col_stat(LP, i+1, LPX_NS);
> lpx_warm_up(LP);
>
> I'm still getting reduced costs of zero. Any suggestions?
In case of lpx_set_col_stat the status LPX_NS means only a non-basic
column, i.e. this flag does not change the column type.
The correct code is the following:
for (i = 0; i < numcols; i++)
{ /* obtain column value in mip solution */
x = lpx_mip_col_val(LP, i+1);
/* fix the column at that value */
lpx_set_col_bnds(LP, i+1, LPX_FX, x, x);
}
/* make all rows non-active and all columns non-basic */
lpx_std_basis(LP);
/* compute lp solution components */
lpx_warm_up(LP);