[Pkg-scicomp-devel] Bug#490288: glpk: Fails on assertion

[Ingo Feinerer]

Package: glpk
Version: 4.11-1
Severity: normal


The following linear program triggers an assertion and stops the program
without a proper solution:

var x1 integer;
var x2 integer;

minimize objective : x1 + x2;

s.t. constraint : (8^4 - 1) * x1 - 8^4 * x2 = 0;

s.t. x1NotNegative : x1 >= 1;
s.t. x2NotNegative : x2 >= 1;

end;

Output of above program:

feinerer at resistance:~$ glpsol -m bug.mod -o bug.sol
Reading model section from bug.mod...
11 lines were read
Generating objective...
Generating constraint...
Generating x1NotNegative...
Generating x2NotNegative...
Model has been successfully generated
lpx_simplex: original LP has 4 rows, 2 columns, 6 non-zeros
Objective value = 2.0002442
OPTIMAL SOLUTION FOUND BY LP PRESOLVER
Integer optimization begins...
Objective function is integral
+     0: mip =     not found yet >=              -inf        (1; 0)
+  6922: mip =     not found yet >=   3.000000000e+00        (6924; 0)
Assertion failed: x >= lb; file glpmip2.c; line 230

Note that no bug.sol is created.

-- System Information:
Debian Release: 4.0
  APT prefers stable
  APT policy: (500, 'stable')
Architecture: i386 (i686)
Shell:  /bin/sh linked to /bin/bash
Kernel: Linux 2.6.18-6-686
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)

Versions of packages glpk depends on:
ii  libc6                  2.3.6.ds1-13etch5 GNU C Library: Shared libraries

glpk recommends no packages.

-- no debconf information