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Re: [Bug-glpk] printf statement being ignored with large constraint


From: Andrew Makhorin
Subject: Re: [Bug-glpk] printf statement being ignored with large constraint
Date: Mon, 28 Jan 2008 13:17:33 +0300

> When I add a large constraint (third constraint
> (HTsHaveSameCompanionForAllFamilies) in the attached model) with dimensions
> 40x40x57 (91,200 elements), my printf statement seems to get ignored. 
> gplsol tells me OPTIMAL SOLUTION FOUND in the simplex section and PROBLEM
> HAS NO INTEGER FEASIBLE SOLUTION in the integer section.  When I comment out
> the third constraint, the printf runs as expected.  This seems like a bug. 
> As long as the simplex section finds a solution, the printf should run,
> shouldn't it?

Hmm... Looks like there is something wrong in your model, not in glpsol.

The following model works for me:

var x, integer, >= 1, <= 3;
s.t. foo: x = 2.5;
solve;
printf "x = %g", x;
end;

Reading model section from test.mod...
5 lines were read
Generating foo...
Model has been successfully generated
glp_simplex: original LP has 1 row, 1 column, 1 non-zero
Objective value = 0
OPTIMAL SOLUTION FOUND BY LP PRESOLVER
Integer optimization begins...
+     0: mip =     not found yet >=     tree is empty        (0; 1)
PROBLEM HAS NO INTEGER FEASIBLE SOLUTION
Time used:   0.0 secs
Memory used: 0.1 Mb (104277 bytes)
x = 0
Model has been successfully processed

If solving of your model takes a long time, you can write the
solution to a file with the option '-w filename', and then specify it
with the option '-r filename', in which case it will be passed to the
model without solving.





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