Re: [Help-glpk] bug ? Assertion failed: ap[q] != 0.0; file source/glpspx2.c; line1249

[Andrew Makhorin]

>I get a
>Assertion failed: ap[q] != 0.0; file source/glpspx2.c; line 1249
>when solving a small problem.
>
>However, writing the mps and solving it with glpsol is ok.
>I guess I can't reproduce it because I use LPX_K_DUAL = 1 (i.e. a basis of
a
>previous problem exists).
>
>Is there a bug ? What can I send to make the discovery of the reason easier
>?
>Anyway, I send already the .mps and the ouput of lpx_print_sol (before
>solving).
>hope this helps making glpk better :-)

Thank you very much for your report.

In fact, three columns is not very large size :+) I need a time to
investigate this casus more carefully.

Could you please replace #if 0 by #if 1 in glplpx6a.c, line 1167, run
your problem, and send me the output produced (10-20 lines that precede
the crashing). This would provide me with a necessary information for
thinking.

Since your problem is tiny, try not to use the dual simplex, i.e. use
the primal simplex even the initial basis is dual feasible. I think this
may help.