Re: [Bug-glpk] Model causes glpk to hang

[Heinrich Schuchardt]

Hello Andrew

npp_implied_bounds does not check if col->ll.ll > DBL_MAX.

I suggest to add the missing check in npp_improve_bounds, file glpnpp05.c:

      npp_implied_bounds(npp, row);
      /* and use these bounds to strengthen current column bounds */
      for (aij = row->ptr; aij != NULL; aij = next_aij)
      {  col = aij->col;
         if (col->ll.ll > +DBL_MAX || col->uu.uu < -DBL_MAX)
            return -1;

Best regards

Heinrich Schuchardt

>> -------- Forwarded Message --------
>> From: Yori Zwols <address@hidden>
>> To: address@hidden
>> Subject: Re: Model causes glpk to hang
>> Date: Sun, 17 May 2015 22:46:39 +0100
>>
>> And the following model:
>>
>> var x1 >= 0, integer;
>> var x2 >= 0, integer;
>>
>> subject to c1: x1 - 1.0001 * x2 >= 0.9;
>> subject to c2: x1 - x2 <= 0.8;
>>
>> results in an assertion failure:
>>
>> GLPSOL: GLPK LP/MIP Solver, v4.55
>> Parameter(s) specified in the command line:
>>  --math /home/yori/glpk-fail2.mod
>> Reading model section from /home/yori/glpk-fail2.mod...
>> /home/yori/glpk-fail2.mod:7: warning: unexpected end of file; missing
>> end statement inserted
>> 7 lines were read
>> Generating c1...
>> Generating c2...
>> Model has been successfully generated
>> GLPK Integer Optimizer, v4.55
>> 2 rows, 2 columns, 4 non-zeros
>> 2 integer variables, none of which are binary
>> Preprocessing...
>> Assertion failed: q->lb < q->ub
>> Error detected in file glpnpp03.c at line 557
>> Aborted