[Bug-glpk] Re: Assertion failed mip!=mip

[Andrew Makhorin]

> I am trying to generate Windows executable for glpk 4.40 using Microsoft
> Studio 2008.  I run the executable to solve vpm2.mps of MIPLIB 2003.
> The program displayed the message 

>     Assertion failed mip != mip.

> It is called by ios_driver in glpios03.c.  Will you please tell me some
> hint what might have caused this error message so that I can debug it.

Please report the exact message text. I need to know the line number
where the assertion fails.

> Thanks for your help and time.  I have replaced these deprecated usages
> with new MS usages such as strcpy_s.  

This is not a good idea. Glpk is highly portable and works on all modern
32- and 64-bit platforms. Please do not change its source code if there
is not a reason to do that (Microsoft's quirks is not a reason). Most
likely the error happens due to your changes.

I compiled glpsol 4.40 with MS Visual Studio 2010 and solved vpm2 from
miplib 2003 without any problems. See the log below.


Andrew Makhorin


GLPSOL: GLPK LP/MIP Solver 4.40
Parameter(s) specified in the command line:
 --pcost --mir vpm2.mps --log vpm2.log
Reading problem data from `vpm2.mps'...
Problem: VPM2
Objective: TIME....
235 rows, 378 columns, 1085 non-zeros
168 integer variables, all of which are binary
1413 records were read
ipp_basic_tech:  61 row(s) and 60 column(s) removed
ipp_reduce_bnds: 2 pass(es) made, 53 bound(s) reduced
ipp_basic_tech:  0 row(s) and 0 column(s) removed
ipp_reduce_coef: 2 pass(es) made, 53 coefficient(s) reduced
glp_intopt: presolved MIP has 174 rows, 318 columns, 701 non-zeros
glp_intopt: 168 integer columns, all of which are binary
Scaling...
 A: min|aij| = 2.500e-002  max|aij| = 6.000e+002  ratio = 2.400e+004
GM: min|aij| = 3.754e-001  max|aij| = 2.664e+000  ratio = 7.097e+000
EQ: min|aij| = 1.461e-001  max|aij| = 1.000e+000  ratio = 6.847e+000
2N: min|aij| = 1.000e-001  max|aij| = 1.600e+000  ratio = 1.600e+001
Constructing initial basis...
Size of triangular part = 174
Solving LP relaxation...
      0: obj =  1.600000000e+002  infeas = 2.680e+002 (0)
*   111: obj =  2.578860556e+001  infeas = 0.000e+000 (0)
*   200: obj =  1.026903696e+001  infeas = 1.394e-016 (0)
*   202: obj =  1.026903696e+001  infeas = 2.712e-031 (0)
OPTIMAL SOLUTION FOUND
Integer optimization begins...
MIR cuts enabled
+   202: mip =     not found yet >=              -inf        (1; 0)
+  4827: >>>>>  1.625000000e+001 >=  1.284042735e+001  21.0% (311; 8)
+ 11348: >>>>>  1.575000000e+001 >=  1.312116593e+001  16.7% (724; 45)
+ 12026: >>>>>  1.450000000e+001 >=  1.313328425e+001   9.4% (740; 95)
+ 22834: mip =  1.450000000e+001 >=  1.325369343e+001   8.6% (1259; 398)
+ 31499: >>>>>  1.425000000e+001 >=  1.328870612e+001   6.7% (1730; 427)
+ 33833: >>>>>  1.400000000e+001 >=  1.330393253e+001   5.0% (1609; 839)
+ 44172: mip =  1.400000000e+001 >=  1.333319083e+001   4.8% (1731; 1633)
+ 50920: >>>>>  1.375000000e+001 >=  1.335795710e+001   2.9% (2016; 1669)
+ 61363: mip =  1.375000000e+001 >=  1.340049106e+001   2.5% (1457; 3377)
+ 71869: mip =  1.375000000e+001 >=  1.343780648e+001   2.3% (1621; 3528)
+ 81908: mip =  1.375000000e+001 >=  1.349072531e+001   1.9% (1716; 3730)
+ 92571: mip =  1.375000000e+001 >=  1.353197234e+001   1.6% (1797; 3966)
+102875: mip =  1.375000000e+001 >=  1.356090375e+001   1.4% (1864; 4204)
+112655: mip =  1.375000000e+001 >=  1.360582011e+001   1.0% (1779; 4597)
+122520: mip =  1.375000000e+001 >=  1.364117772e+001   0.8% (1561; 5134)
Time used: 60.0 secs.  Memory used: 7.3 Mb.
+131867: mip =  1.375000000e+001 >=  1.367709874e+001   0.5% (1205; 5913)
+140101: mip =  1.375000000e+001 >=  1.371647757e+001   0.2% (367; 8081)
+141578: mip =  1.375000000e+001 >=     tree is empty   0.0% (0; 10423)
INTEGER OPTIMAL SOLUTION FOUND
Time used:   70.0 secs
Memory used: 7.5 Mb (7889664 bytes)