#18838: GLPK backend does not detect unboundedness in simplex-only mode
-------------------------------------+-------------------------------------
Reporter: mkoeppe | Owner:
Type: defect | Status: needs_work
Priority: major | Milestone: sage-6.8
Component: numerical | Resolution:
Keywords: lp | Merged in:
Authors: Matthias Koeppe, | Reviewers: Dima Pasechnik
Yuan Zhou | Work issues:
Report Upstream: N/A | Commit:
Branch: | a25f47fa00d2fa7e5486f64405fa73b2ff3f909a
u/yzh/glpk_backend_does_not_detect_unboundedness_in_simplex_only_mode|
Stopgaps:
Dependencies: |
-------------------------------------+-------------------------------------
Comment (by mkoeppe):
Patchbot reports that two tests fail:
{{{
sage -t --long src/sage/numerical/mip.pyx
**********************************************************************
File "src/sage/numerical/mip.pyx", line 2416, in
sage.numerical.mip.MIPSolverException.__init__
Failed example:
p.solve()
Expected:
Traceback (most recent call last):
...
MIPSolverException: 'GLPK : There is no feasible integer solution to
this Linear Program'
Got:
<BLANKLINE>
Traceback (most recent call last):
File "/home/vincent/sage_patchbot/local/lib/python2.7/site-
packages/sage/doctest/forker.py", line 496, in _run
self.compile_and_execute(example, compiler, test.globs)
File "/home/vincent/sage_patchbot/local/lib/python2.7/site-
packages/sage/doctest/forker.py", line 858, in compile_and_execute
exec(compiled, globs)
File "<doctest sage.numerical.mip.MIPSolverException.__init__[7]>",
line 1, in <module>
p.solve()
File "sage/numerical/mip.pyx", line 2098, in
sage.numerical.mip.MixedIntegerLinearProgram.solve
(build/cythonized/sage/numerical/mip.c:14050)
self._backend.solve()
File "sage/numerical/backends/glpk_backend.pyx", line 1018, in
sage.numerical.backends.glpk_backend.GLPKBackend.solve
(build/cythonized/sage/numerical/backends/glpk_backend.cpp:8533)
raise MIPSolverException("GLPK : Solution is undefined. The LP
(relaxation) problem instance has no primal feasible solution")
MIPSolverException: 'GLPK : Solution is undefined. The LP (relaxation)
problem instance has no primal feasible solution'
**********************************************************************
File "src/sage/numerical/mip.pyx", line 2432, in
sage.numerical.mip.MIPSolverException.__init__
Failed example:
p.solve()
Expected:
Traceback (most recent call last):
...
MIPSolverException: 'GLPK : There is no feasible integer solution to
this Linear Program'
Got:
<BLANKLINE>
Traceback (most recent call last):
File "/home/vincent/sage_patchbot/local/lib/python2.7/site-
packages/sage/doctest/forker.py", line 496, in _run
self.compile_and_execute(example, compiler, test.globs)
File "/home/vincent/sage_patchbot/local/lib/python2.7/site-
packages/sage/doctest/forker.py", line 858, in compile_and_execute
exec(compiled, globs)
File "<doctest sage.numerical.mip.MIPSolverException.__init__[14]>",
line 1, in <module>
p.solve()
File "sage/numerical/mip.pyx", line 2098, in
sage.numerical.mip.MixedIntegerLinearProgram.solve
(build/cythonized/sage/numerical/mip.c:14050)
self._backend.solve()
File "sage/numerical/backends/glpk_backend.pyx", line 1018, in
sage.numerical.backends.glpk_backend.GLPKBackend.solve
(build/cythonized/sage/numerical/backends/glpk_backend.cpp:8533)
raise MIPSolverException("GLPK : Solution is undefined. The LP
(relaxation) problem instance has no primal feasible solution")
MIPSolverException: 'GLPK : Solution is undefined. The LP (relaxation)
problem instance has no primal feasible solution'
**********************************************************************
1 item had failures:
2 of 16 in sage.numerical.mip.MIPSolverException.__init__
[467 tests, 2 failures, 1.39 s]
}}}
--
Ticket URL: <http://trac.sagemath.org/ticket/18838#comment:25>
Sage <http://www.sagemath.org>
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and MATLAB
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