[Bug-glpk] glpk 4.11 failed assertion

[Sven Verdoolaege]

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