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[Help-glpk] "verbose" mode?


From: Ingo . Thomas
Subject: [Help-glpk] "verbose" mode?
Date: Mon, 18 Oct 2004 11:14:23 +0200

Hi there!

many thanks for making glpk available. I like it and intent to use it as a
replacement or alternative for a commercial package in a process simulator
toolbox. It would be even more useful if there would be a feature that
could help me to find inconsistent constraints in large LPs, similar to,
for instance, CPLEX.

For instance, CPLEX reports for an infeasible Problem something like

presolve: constraint R_fb[3,7] cannot hold:
        body <= 0 cannot be >= 30; difference = -30
presolve: constraint R_fb[3,6] cannot hold:
        body <= 0 cannot be >= 45; difference = -45
presolve: constraint R_fb[3,5] cannot hold:
        body <= 0 cannot be >= 46; difference = -46
presolve: constraint R_fb[3,4] cannot hold:
        body <= 0 cannot be >= 45; difference = -45
presolve: constraint R_fb[3,3] cannot hold:
        body <= 0 cannot be >= 56; difference = -56

whereas glpk reports

    85 R_fb[3,4]                   0            -0             =
    86 R_fb[3,5]                   0            -0             =
    87 R_fb[3,6]                   0            -0             =
    88 R_fb[3,7]                   0            -0             =

which, as far as I understand the output, does not give me any hint whats
wrong with my LP.

Do you have any advice?

Best regards, Ingo





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