Re: [Bug-glpk] [Fwd: preprocessing goes into infinite loop]

[glpk xypron]

Hello Andrew,

I suggest that the problem due to missing bounds should be gracefully
detected and a meaningful message should be displayed to the user.

Best regards

Xypron

-------- Original-Nachricht --------
> Datum: Sat, 14 Jan 2012 18:13:14 +0300
> Von: Andrew Makhorin <address@hidden>
> An: glpk xypron <address@hidden>
> CC: address@hidden, John Perry <address@hidden>
> Betreff: Re: [Bug-glpk] [Fwd: preprocessing goes into infinite loop]

> Hi Xypron,
> 
> > when running glp_simplex on the problem, I get this output:
> > GLPK Simplex Optimizer, v4.47
> > 45 rows, 5 columns, 123 non-zeros
> >       0: obj =   5.000000000e+00  infeas =  3.750e+01 (0)
> >      37: obj =   1.400000000e+01  infeas =  8.833e+00 (0)
> > PROBLEM HAS NO FEASIBLE SOLUTION
> > 
> > I then used John's coding to write the appended file in CPLEX format.
> > 
> > glpsol --lp test.lp leads to the following error in the presolver:
> > 
> > Preprocessing...
> > Assertion failed: q->lb < q->ub
> > Error detected in file ..\src\glpnpp03.c at line 556
> 
> This diagnostics is not relevant due to floating-point overflow (please
> see my recent posting to bug-glpk). The glpk code is not intended to
> work with Inf's and NaN's, so such values completely destroy the program
> logic.
> 
> > 
> > I would not have expected such an error.
> > 
> 
> 
> Andrew Makhorin
> 

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