Re: [Help-glpk] Transfer solution file between clp and glpsol

[Andrew Makhorin]

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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