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Re: [Help-glpk] MPS model has zero objective function in version 4_32

From: Xypron
Subject: Re: [Help-glpk] MPS model has zero objective function in version 4_32
Date: Wed, 19 Nov 2008 23:20:46 +0100
User-agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv: Gecko/20081030 SeaMonkey/1.1.13

Marc Goetschalckx wrote:
I am writing an identical GLPK problem out in MPS format and LP format from the API.  I then read and solve the models with glpsol.  The LP model solves correctly.  The MPS model solves but has objective function zero.  A similar behavior occurred in earlier version unless the parameter LPS_K_MPSOBJ was set to 1.  However, the function lpx_set_int_parm is no longer available in version 4.32.  How do I specify the objective function in the MPS model with version 4_32 (and I assume the current version as well).  The following lines are the output of the LP and the MPS models solved with glpsol.

Hello Marc,

on GLPK 4.33 I issued:
./glpsol -m transp.mod --check --wmps transp.mps --wcpxlp transp.lp
./glpsol transp.mps --min
./glpsol --cpxlp transp.lp

Both the MPS and the LP file gave the same objective value.

The first non constrained row (type N) is the objective. In the MPS file format there is no parameter defining if a minimum or the maximum is to be obtained. Please, specify --min or --max on the command line of glpsol.

Best regards


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