[Pkg-scicomp-devel] Bug#490288: Bug#490288: glpk: Fails on assertion

[Rafael Laboissiere]

package glpk
tags 490288 confirmed upstream
thanks

* Ingo Feinerer <feinerer at logic.at> [2008-07-11 12:00]:

> Package: glpk
> Version: 4.11-1
> Severity: normal
> 
> 
> The following linear program triggers an assertion and stops the program
> without a proper solution:
> 
> var x1 integer;
> var x2 integer;
> 
> minimize objective : x1 + x2;
> 
> s.t. constraint : (8^4 - 1) * x1 - 8^4 * x2 = 0;
> 
> s.t. x1NotNegative : x1 >= 1;
> s.t. x2NotNegative : x2 >= 1;
> 
> end;
> 
> Output of above program:
> 
> feinerer at resistance:~$ glpsol -m bug.mod -o bug.sol
> Reading model section from bug.mod...
> 11 lines were read
> Generating objective...
> Generating constraint...
> Generating x1NotNegative...
> Generating x2NotNegative...
> Model has been successfully generated
> lpx_simplex: original LP has 4 rows, 2 columns, 6 non-zeros
> Objective value = 2.0002442
> OPTIMAL SOLUTION FOUND BY LP PRESOLVER
> Integer optimization begins...
> Objective function is integral
> +     0: mip =     not found yet >=              -inf        (1; 0)
> +  6922: mip =     not found yet >=   3.000000000e+00        (6924; 0)
> Assertion failed: x >= lb; file glpmip2.c; line 230

I confirm the problem with glpk 4.29, which has just been uploaded to
unstable.  The error message is slightly different:

Reading model section from bug.mod...
11 lines were read
Generating objective...
Generating constraint...
Generating x1NotNegative...
Generating x2NotNegative...
Model has been successfully generated
glp_simplex: original LP has 4 rows, 2 columns, 6 non-zeros
Objective value = 2.0002442
OPTIMAL SOLUTION FOUND BY LP PRESOLVER
Integer optimization begins...
+     0: mip =     not found yet >=              -inf        (1; 0)
Assertion failed: x >= lb
Error detected in file glpios03.c at line 257
Aborted

I am therefore forwarding this bug report to the upstream author.
Andrew: could you please look at this?  Please, respect the Reply-To when
replying to this message.

Thanks,

-- 
Rafael