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Re: [Help-glpk] Transfer solution file between clp and glpsol
From: |
Andrew Makhorin |
Subject: |
Re: [Help-glpk] Transfer solution file between clp and glpsol |
Date: |
Sun, 21 Jan 2018 06:51:14 +0300 |
On Sat, 2018-01-20 at 21:36 -0500, Greg Gruber wrote:
> Hello,
>
>
> I have a problem which is solving much faster in clp than with glpsol.
> I would like to continue to use GMPL for my formulation and
> post-processing. If I run just using glpsol, it takes far too long;
> if I run with clp (compiled for GMPL support), I get a solution
> quickly, however clp then crashes. If i do the following:
>
>
> glpsol --check --wfreemps foo.mps -m mymod.mod -d mydat.dat
> clp foo.mps
>
>
> It solves quickly.
>
>
> My problem is that I want to use GMPL scrip for some post-processing
> as well. Is there any way to
> 1. use glpsol to generate an mps (or lp) file
> 2. use clp to solve the underlying problem
> 3. SAVE the solution to a file
First, you need to save the solution found by clp in the glpk format. If
it is a basic solution found by a simplex-like solver, it should be
saved in the glpk basic solution format (see glpk 4.64 reference manual,
subsection 3.3.2 glp_read_sol — read basic solution in GLPK format). If
it is a mip solution, it should be saved in the glpk mip solution format
(ibid., subsection 3.3.8 glp_read_mip — read MIP solution in GLPK
format).
> 4. use glpsol to READ the solution and do post-processing using
> GMPL ?
Then you may use the following command:
glpsol -m mymod.mod -d mydat.dat -r SOLUTION
where SOLUTION is the name of a solution file in glpk format. In this
case glpsol just takes the known solution to perform model statements
specified below the solve statement in mathprog model.
>
>
> Thanks,
> Greg
>
>
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