[Bug-glpk] internal error: x <= ub; file glpios03.c, line 264

[Jack Whitham]

I may have found a bug causing an assertion failure in GLPK 4.24. 
I see the following message at the end of output; abort() is called.

> Model has been successfully generated
> glp_simplex: original LP has 493 rows, 383 columns, 1210 non-zeros
> glp_simplex: presolved LP has 374 rows, 281 columns, 865 non-zeros
> lpx_adv_basis: size of triangular part = 254
>       0:   objval =   6.065620000e+05   infeas =   1.000000000e+00 (106)
>       4:   objval =   7.346340000e+05   infeas =   0.000000000e+00 (118)
> *     4:   objval =   7.346340000e+05   infeas =   0.000000000e+00 (118)
> *    24:   objval =   1.835197111e+06   infeas =   4.547473509e-13 (117)
> OPTIMAL SOLUTION FOUND
> Integer optimization begins...
> +    24: mip =     not found yet <=              +inf        (1; 0)
> GLPK internal error: x <= ub; file glpios03.c, line 264

This might be a problem with my model, which is complex and generated
by another program. I noticed that the problem occurs with model "A.mod" 
but not with model "B.mod", which seems to me to be more complex. Other
models generated by the same program also work. I loaded the 
models using commands like:

    ./glpsol --math A.mod

My version is compiled on i386 Debian from glpk-4.24.tar.gz, md5 
765dcecc20dc6b80362e65c755f41976. Please let me know if I can
provide more information.


Thankyou very much, and happy holidays,


Jack Whitham


-- 
Jack Whitham
address@hidden

A.mod.gz
Description: application/gunzip

B.mod.gz
Description: application/gunzip