[SCIP] problems with "infinity"

[James Cussens]

Hi,

I have a linear constraint:

 [linear] <scoreub>: <score>[C] -1e+20<ch#0>[B] -1e+20<ch#1>[B] -1e+20<ch#2>[B] -1e+20<ch#3>[B] -1e+20<ch#4>[B] -1e+20<ch#5>[B] -1e+20<ch#6>[B] <= 0;

which (in debug mode) is causing the following problem:

gobnilp: src/scip/set.c:6168: SCIPsetIsEQ: Assertion `((!SCIPsetIsInfinity(set, val1) || !SCIPsetIsInfinity(set, val2)) && (!SCIPsetIsInfinity(set, -val1) || !SCIPsetIsInfinity(set, -val2))) || val1 == val2' failed.

Thread 1 "gobnilp" received signal SIGABRT, Aborted.
__pthread_kill_implementation (no_tid=0, signo=6, threadid=140737350973376) at ./nptl/pthread_kill.c:44
44    ./nptl/pthread_kill.c: No such file or directory.
(gdb) bt
#0  __pthread_kill_implementation (no_tid=0, signo=6, threadid=140737350973376) at ./nptl/pthread_kill.c:44
#1  __pthread_kill_internal (signo=6, threadid=140737350973376) at ./nptl/pthread_kill.c:78
#2  __GI___pthread_kill (threadid=140737350973376, signo=signo at entry=6) at ./nptl/pthread_kill.c:89
#3  0x00007ffff6a42476 in __GI_raise (sig=sig at entry=6) at ../sysdeps/posix/raise.c:26
#4  0x00007ffff6a287f3 in __GI_abort () at ./stdlib/abort.c:79
#5  0x00007ffff6a2871b in __assert_fail_base (fmt=0x7ffff6bdd150 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n",
    assertion=0x555559676ce0 "((!SCIPsetIsInfinity(set, val1) || !SCIPsetIsInfinity(set, val2)) && (!SCIPsetIsInfinity(set, -val1) || !SCIPsetIsInfinity(set, -val2))) || val1 == val2", file=0x55555966f220 "src/scip/set.c", line=6168, function=<optimised out>) at ./assert/assert.c:92
#6  0x00007ffff6a39e96 in __GI___assert_fail (
    assertion=0x555559676ce0 "((!SCIPsetIsInfinity(set, val1) || !SCIPsetIsInfinity(set, val2)) && (!SCIPsetIsInfinity(set, -val1) || !SCIPsetIsInfinity(set, -val2))) || val1 == val2", file=0x55555966f220 "src/scip/set.c", line=6168, function=0x555559678098 <__PRETTY_FUNCTION__.72> "SCIPsetIsEQ")
    at ./assert/assert.c:101
#7  0x0000555557a873d8 in SCIPsetIsEQ (set=0x55555b42fc70, val1=-2.6911787705190607e+22, val2=-1e+20) at src/scip/set.c:6168
#8  0x00005555578f6775 in SCIPisEQ (scip=0x55555b28f340, val1=-2.6911787705190607e+22, val2=-1e+20) at src/scip/scip_numerics.c:454
#9  0x0000555556e3fe2f in checkEqualObjective (scip=0x55555b28f340, consdata=0x55555b3fd7f8, scale=0x7fffffffaad8, offset=0x7fffffffaad0)
    at src/scip/cons_linear.c:10322

so it looks like the problem is caused by checkEqualObjective generating a value ( -2.6911787705190607e+22 ) which is less than -1+e20 (ie less than "negative infinity"). I can easily get round this (and indeed should do since constraints with infinite coefficients aren't a great idea!) but it might be worth adding some sort of check for "infinite" coefficients in linear constraints.

James

James Cussens
Room MVB 3.26
School of Computer Science, University of Bristol
Phone: +44 (0)117 455 8723
https://jcussens.github.io/
Funded PhDs available in Bristol in the following areas: Data Science<http://www.bristol.ac.uk/cdt/compass/>, Interactive AI<http://www.bristol.ac.uk/cdt/interactive-ai/>, Cyber Security<http://www.bristol.ac.uk/cdt/cyber-security/> or Digital Health<http://www.bristol.ac.uk/cdt/digital-health/>.
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