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[Help-glpk] [Fwd: Re: performance issue]
From: |
Andrew Makhorin |
Subject: |
[Help-glpk] [Fwd: Re: performance issue] |
Date: |
Wed, 07 Sep 2016 18:46:59 +0300 |
-------- Forwarded Message --------
From: Giorgio Sartor <address@hidden>
To: Joshua Friedman <address@hidden>
Cc: address@hidden
Subject: Re: [Help-glpk] performance issue
Date: Wed, 7 Sep 2016 22:55:36 +0800
Have you tried option --fpump?
The heuristic part of GLPK (the one able to find feasible solutions
quickly) is not as strong as the MIP engine. We are working on that. ;-)
- G. S. -
On 7 Sep 2016, at 9:44 PM, Joshua Friedman <address@hidden> wrote:
> I am working on a bit integer program and my data has 45000 variables
> (see below). I am basically just looking for a feasible solution, my
> objective is constant.
>
>
> My question: it took 10 minutes to run using the glpk solver. I
> converted to a CBC form and it solved it in 1 minute, and using Gurobi
> it took about 1 second (but it used all 8 threads). Am I doing
> something wrong with glpk for bit integer programs? Is there an
> option that is more efficient?
>
> Model has been successfully generated
> GLPK Integer Optimizer, v4.60
> 68514 rows, 45040 columns, 372605 non-zeros
> 45040 integer variables, all of which are binary
> Preprocessing...
> 9020 hidden covering inequaliti(es) were detected
> 1397 constraint coefficient(s) were reduced
> 15253 rows, 29410 columns, 161743 non-zeros
> 29410 integer variables, all of which are binary
> Scaling...
> A: min|aij| = 1.000e+00 max|aij| = 1.000e+01 ratio = 1.000e+01
> Problem data seem to be well scaled
> Constructing initial basis...
> Size of triangular part is 15253
> Solving LP relaxation...
> GLPK Simplex Optimizer, v4.60
> 15253 rows, 29410 columns, 161743 non-zeros
> 0: obj = 0.000000000e+00 inf = 6.040e+02 (247)
> 500: obj = 0.000000000e+00 inf = 3.980e+02 (115) 1
> 837: obj = 0.000000000e+00 inf = 0.000e+00 (0) 1
> OPTIMAL LP SOLUTION FOUND
> Integer optimization begins...
> + 837: mip = not found yet >= -inf (1; 0)
> + 1389: mip = not found yet >= 0.000000000e+00 (30; 0)
> + 2309: mip = not found yet >= 0.000000000e+00 (50; 7)
> + 2835: mip = not found yet >= 0.000000000e+00 (77; 14)
> + 3106: mip = not found yet >= 0.000000000e+00 (113; 14)
>
>
> --
> Joshua Friedman PhD
>
> address@hidden
> http://www.math.sunysb.edu/~joshua
> _______________________________________________
> Help-glpk mailing list
> address@hidden
> https://lists.gnu.org/mailman/listinfo/help-glpk
>
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