LinearFunction.__hash__ overflow

[jdemeyer]

On cicero (32-bit Linux), the following random test might fail:

sage -t  --long -force_lib devel/sage/sage/graphs/generic_graph.py
**********************************************************************
File "/home/buildbot/build/sage/cicero-1/cicero_full/build/sage-5.5.rc1/devel/sage-main/sage/graphs/generic_graph.py", line 4436:
    sage: arborescences = g.edge_disjoint_spanning_trees(k)  # long time (up to 15s on sage.math, 2011)
Exception raised:
    Traceback (most recent call last):
      File "/home/buildbot/build/sage/cicero-1/cicero_full/build/sage-5.5.rc1/local/bin/ncadoctest.py", line 1231, in run_one_test
        self.run_one_example(test, example, filename, compileflags)
      File "/home/buildbot/build/sage/cicero-1/cicero_full/build/sage-5.5.rc1/local/bin/sagedoctest.py", line 38, in run_one_example
        OrigDocTestRunner.run_one_example(self, test, example, filename, compileflags)
      File "/home/buildbot/build/sage/cicero-1/cicero_full/build/sage-5.5.rc1/local/bin/ncadoctest.py", line 1172, in run_one_example
        compileflags, 1) in test.globs
      File "<doctest __main__.example_68[8]>", line 1, in <module>
        arborescences = g.edge_disjoint_spanning_trees(k)  # long time (up to 15s on sage.math, 2011)###line 4436:
    sage: arborescences = g.edge_disjoint_spanning_trees(k)  # long time (up to 15s on sage.math, 2011)
      File "/home/buildbot/build/sage/cicero-1/cicero_full/build/sage-5.5.rc1/local/lib/python/site-packages/sage/graphs/generic_graph.py", line 4511, in edge_disjoint_spanning_trees
        p.add_constraint(r_edges[j][(u,v)] + r_edges[j][(v, u)] - edges[j][(u,v)], min=0)
      File "mip.pyx", line 1976, in sage.numerical.mip.MIPVariable.__getitem__ (sage/numerical/mip.c:10250)
      File "linear_functions.pyx", line 821, in sage.numerical.linear_functions.LinearFunction.__hash__ (sage/numerical/linear_functions.c:6740)
    OverflowError: Python int too large to convert to C long
**********************************************************************

Apply

• attachment: trac_13797_hash_overflow.patch

CC: @vbraun @dimpase

Component: linear programming

Author: Volker Braun

Reviewer: Dmitrii Pasechnik

Merged: sage-5.5.rc1

Issue created by migration from https://trac.sagemath.org/ticket/13797

[nathanncohen]

Author: vbraun, dimpase

[nathanncohen]

Changed author from vbraun, dimpase to none

[vbraun]

comment:3

I also fixed the comparison (which has to fulfill a contract with __hash__).

[vbraun]

comment:4

I've tested in in a 32-bit VM and it works for me...

[vbraun]

Author: Volker Braun

[vbraun]

Attachment: trac_13797_hash_overflow.patch.gz

Updated patch

[vbraun]

comment:5

Accidentally uploaded the wrong version, fixed now.

[dimpase]

comment:8

Looks OK.

[jdemeyer]

Reviewer: Dmitrii Pasechnik

[jdemeyer]

Merged: sage-5.5.rc1