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[Bug-glpk] glpk 4.11 failed assertion
From: |
Sven Verdoolaege |
Subject: |
[Bug-glpk] glpk 4.11 failed assertion |
Date: |
Thu, 3 Aug 2006 17:53:42 +0400 |
I'm having a problem with a failed assertion in glpk 4.11.
I'm using the library interface and after setting up the problem and calling
lpx_adv_basis(lp);
I do
lpx_simplex(lp);
and for one particular problem, I get
Assertion failed: spx->p != 0; file glpspx2.c; line 668
When I write out the problem (attached), however, and run gplsol
on it, I get
lpx_read_freemps: reading problem data from `/tmp/lp.mps'...
lpx_read_freemps: problem name not specified
lpx_read_freemps: 43 rows, 12 columns, 198 non-zeros
lpx_read_freemps: 193 records were read
lpx_simplex: original LP has 43 rows, 12 columns, 198 non-zeros
lpx_simplex: presolved LP has 38 rows, 12 columns, 192 non-zeros
lpx_adv_basis: size of triangular part = 38
0: objval = 0.000000000e+00 infeas = 1.000000000e+00 (0)
8: objval = 0.000000000e+00 infeas = 1.526958211e-02 (0)
PROBLEM HAS NO FEASIBLE SOLUTION
lpx_simplex: cannot recover undefined or non-optimal solution
Time used: 0.0 secs
Memory used: 0.1M (106164 bytes)
Now, I was expecting a solution, but I assume it got lost
because I have to convert the coefficients of the problem
to doubles as it appears that glpk doesn't support arbitrary
precision integer arithmetic.
Still, getting an unexpected answer would be nicer than a failed
assertion.
I can reproduce the problem by running the polyhedron_sample
program from the latest git version of my barvinok library
(http://www.liacs.nl/~sverdool/gitweb.cgi?p=barvinok.git;a=summary)
with the following input:
18 8
1 0 0 0 0 0 1 -28
1 16 13 0 -297 0 -99 -128
1 0 0 1 0 0 0 -33
1 5 0 0 18 0 6 7
1 12 0 0 45 0 12 19
1 17 0 0 63 -3 21 27
1 6 0 0 20 0 9 16
1 -24 -18 0 405 0 135 158
1 -29 0 5 -108 0 -36 -41
1 0 0 0 0 1 0 -28
1 0 0 0 1 0 0 -36
1 -102 -56 0 1161 0 387 497
1 -51 0 0 -189 9 -63 -73
1 -6 0 0 -20 0 -9 -10
1 29 0 -5 108 0 36 45
1 -8 0 0 -27 0 -9 -92
1 7 -7 0 216 0 72 99
1 -60 0 0 -225 0 -60 -92
Unfortunately, as decribed above, the error disappears
after dumping and rereading the problem.
Please CC me as I'm not subscribed.
skimo
lp.mps
Description: Text document
- [Bug-glpk] glpk 4.11 failed assertion,
Sven Verdoolaege <=