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* Problem: UNKNOWN
* Class: LP
* Rows: 42
* Columns: 12
* Non-zeros: 196
* Format: Fixed MPS
*
NAME
ROWS
N R0000000
G R0000001
G R0000002
G R0000003
G R0000004
G R0000005
G R0000006
G R0000007
G R0000008
G R0000009
G R0000010
G R0000011
G R0000012
G R0000013
G R0000014
G R0000015
G R0000016
G R0000017
G R0000018
G R0000019
G R0000020
G R0000021
G R0000022
G R0000023
G R0000024
G R0000025
G R0000026
G R0000027
G R0000028
G R0000029
G R0000030
G R0000031
G R0000032
G R0000033
G R0000034
G R0000035
G R0000036
G R0000037
G R0000038
G R0000039
G R0000040
G R0000041
G R0000042
COLUMNS
C0000001 R0000000 1 R0000021 -1
C0000001 R0000020 467491695 R0000017 141868868
C0000001 R0000016 7377181110 R0000012 4
C0000001 R0000011 3404852820 R0000010 2931956595
C0000001 R0000008 1337620752 R0000004 283737735
C0000001 R0000003 3461600367 R0000002 263470753
C0000001 R0000001 2837377350
C0000002 R0000020 -346 R0000019 1
C0000002 R0000018 2620431000 R0000017 733669859415
C0000002 R0000016 3.8287919E13 R0000015 -1266541650
C0000002 R0000014 262043100 R0000013 2227366350
C0000002 R0000012 -14136034140 R0000011 1.7671186E13
C0000002 R0000010 1.5216855E13 R0000009 1266541650
C0000002 R0000008 6.9373243E12 R0000007 -262043100
C0000002 R0000006 -742455450 R0000005 -524086200
C0000002 R0000004 1.4723805E12 R0000003 1.7965706E13
C0000002 R0000002 1.3710301E12 R0000001 1.4725988E13
C0000003 R0000020 -110498037 R0000018 7.1551264E17
C0000003 R0000017 -4.828626E17 R0000016 1.2322862E19
C0000003 R0000015 -3.590572E17 R0000014 7.1551264E16
C0000003 R0000013 6.0818574E17 R0000012 -3.859865E18
C0000003 R0000011 5.6434433E18 R0000010 4.8596317E18
C0000003 R0000009 3.5905725E17 R0000008 8.7162448E17
C0000003 R0000007 -7.155126E16 R0000006 -2.027286E17
C0000003 R0000005 -1.431025E17 R0000004 4.1066089E17
C0000003 R0000003 5.7401459E18 R0000002 1.4243038E18
C0000003 R0000001 4.7028694E18
C0000004 R0000018 -225 R0000017 216
C0000004 R0000016 -27 R0000015 108
C0000004 R0000014 -20 R0000013 -189
C0000004 R0000012 1161 R0000011 1
C0000004 R0000009 -108 R0000008 405
C0000004 R0000007 20 R0000006 63
C0000004 R0000005 45 R0000004 18
C0000004 R0000002 -297
C0000005 R0000018 -42000 R0000017 50365
C0000005 R0000016 -8120 R0000015 25200
C0000005 R0000014 -6300 R0000013 -44097
C0000005 R0000012 270900 R0000011 -840
C0000005 R0000010 -723 R0000009 -25200
C0000005 R0000008 94170 R0000007 6300
C0000005 R0000006 14699 R0000005 8400
C0000005 R0000004 4130 R0000003 -854
C0000005 R0000002 -69365
C0000006 R0000018 -60 R0000017 72
C0000006 R0000016 -9 R0000015 36
C0000006 R0000014 -9 R0000013 -63
C0000006 R0000012 387 R0000009 -36
C0000006 R0000008 135 R0000007 9
C0000006 R0000006 21 R0000005 12
C0000006 R0000004 6 R0000002 -99
C0000006 R0000001 1
C0000007 R0000000 -1 R0000042 -1
C0000007 R0000041 467491695 R0000038 141868868
C0000007 R0000037 7377181110 R0000033 4
C0000007 R0000032 3404852820 R0000031 2931956595
C0000007 R0000029 1337620752 R0000025 283737735
C0000007 R0000024 3461600367 R0000023 263470753
C0000007 R0000022 2837377350
C0000008 R0000041 -346 R0000040 1
C0000008 R0000039 2620431000 R0000038 733669859415
C0000008 R0000037 3.8287919E13 R0000036 -1266541650
C0000008 R0000035 262043100 R0000034 2227366350
C0000008 R0000033 -14136034140 R0000032 1.7671186E13
C0000008 R0000031 1.5216855E13 R0000030 1266541650
C0000008 R0000029 6.9373243E12 R0000028 -262043100
C0000008 R0000027 -742455450 R0000026 -524086200
C0000008 R0000025 1.4723805E12 R0000024 1.7965706E13
C0000008 R0000023 1.3710301E12 R0000022 1.4725988E13
C0000009 R0000041 -110498037 R0000039 7.1551264E17
C0000009 R0000038 -4.828626E17 R0000037 1.2322862E19
C0000009 R0000036 -3.590572E17 R0000035 7.1551264E16
C0000009 R0000034 6.0818574E17 R0000033 -3.859865E18
C0000009 R0000032 5.6434433E18 R0000031 4.8596317E18
C0000009 R0000030 3.5905725E17 R0000029 8.7162448E17
C0000009 R0000028 -7.155126E16 R0000027 -2.027286E17
C0000009 R0000026 -1.431025E17 R0000025 4.1066089E17
C0000009 R0000024 5.7401459E18 R0000023 1.4243038E18
C0000009 R0000022 4.7028694E18
C0000010 R0000039 -225 R0000038 216
C0000010 R0000037 -27 R0000036 108
C0000010 R0000035 -20 R0000034 -189
C0000010 R0000033 1161 R0000032 1
C0000010 R0000030 -108 R0000029 405
C0000010 R0000028 20 R0000027 63
C0000010 R0000026 45 R0000025 18
C0000010 R0000023 -297
C0000011 R0000039 -42000 R0000038 50365
C0000011 R0000037 -8120 R0000036 25200
C0000011 R0000035 -6300 R0000034 -44097
C0000011 R0000033 270900 R0000032 -840
C0000011 R0000031 -723 R0000030 -25200
C0000011 R0000029 94170 R0000028 6300
C0000011 R0000027 14699 R0000026 8400
C0000011 R0000025 4130 R0000024 -854
C0000011 R0000023 -69365
C0000012 R0000039 -60 R0000038 72
C0000012 R0000037 -9 R0000036 36
C0000012 R0000035 -9 R0000034 -63
C0000012 R0000033 387 R0000030 -36
C0000012 R0000029 135 R0000028 9
C0000012 R0000027 21 R0000026 12
C0000012 R0000025 6 R0000023 -99
C0000012 R0000022 1
RHS
RHS1 R0000001 28 R0000002 128
RHS1 R0000003 33 R0000004 -7
RHS1 R0000005 -19 R0000006 -27
RHS1 R0000007 -16 R0000008 -158
RHS1 R0000009 41 R0000010 28
RHS1 R0000011 36 R0000012 -497
RHS1 R0000013 73 R0000014 10
RHS1 R0000015 -45 R0000016 92
RHS1 R0000017 -99 R0000018 92
RHS1 R0000019 5467566 R0000020 -973764
RHS1 R0000021 -1.067787E22 R0000022 28
RHS1 R0000023 128 R0000024 33
RHS1 R0000025 -7 R0000026 -19
RHS1 R0000027 -27 R0000028 -16
RHS1 R0000029 -158 R0000030 41
RHS1 R0000031 28 R0000032 36
RHS1 R0000033 -497 R0000034 73
RHS1 R0000035 10 R0000036 -45
RHS1 R0000037 92 R0000038 -99
RHS1 R0000039 92 R0000040 5467566
RHS1 R0000041 -973764 R0000042 -1.067787E22
BOUNDS
FR BND1 C0000001
FR BND1 C0000002
FR BND1 C0000003
FR BND1 C0000004
FR BND1 C0000005
FR BND1 C0000006
FR BND1 C0000007
FR BND1 C0000008
FR BND1 C0000009
FR BND1 C0000010
FR BND1 C0000011
FR BND1 C0000012
ENDATA
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