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Re: [Help-glpk] spx_invert: the basis matrix is singular

From: Andrew Makhorin
Subject: Re: [Help-glpk] spx_invert: the basis matrix is singular
Date: Mon, 28 Apr 2008 22:35:40 +0400

> I spent long time to fix this error, but still failed.

> spx_invert: the basis matrix is singular
> spx_simplex: numerical problems with basis matrix
> spx_simplex: sorry, basis recovery procedure not implemented yet
> bfd_ftran: the factorization is not valid

> Part of the code is shown as followed. The purpose is to find out
> the projection of the solution space of the problem on two dimensional
> space. The method is optimize the linear function of these two
> variable. Thus, the coefficients of the objective function changed
> every loop.

Could you please include the following two statements:

   lpx_write_cpxlp(lp, "foo.lp");
   lpx_print_sol(lp, "foo.sol");

immediately before a call to lpx_simplex that fails. This would allow
inspecting the instance and the current basis and possibly might explain
the cause of failure.

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