#12823: Allow constants for objective function & deletion of rows in
MixedIntegerLinearProgram
------------------------------------------+---------------------------------
Reporter: john_perry | Owner: ncohen
Type: defect | Status: needs_review
Priority: major | Milestone: sage-5.0
Component: linear programming | Resolution:
Keywords: solver objective | Work issues: failing doctests
Report Upstream: N/A | Reviewers:
Authors: john_perry, ncohen | Merged in:
Dependencies: #12220, #12736, #12833 | Stopgaps:
------------------------------------------+---------------------------------
Comment (by dcoudert):
Ok, I'm now able to install successfully the patch !
Tests are OK with GLPK but not with CPLEX.
{{{
sage -t -optional "devel/sage-
myclone/sage/numerical/backends/cplex_backend.pyx"
IBM ILOG License Manager: "IBM ILOG Optimization Suite for Academic
Initiative" is accessing CPLEX 12 with option(s): "e m b q ".
**********************************************************************
File "/path-to-sage/devel/sage-
myclone/sage/numerical/backends/cplex_backend.pyx", line 435:
sage: p.solve() # optional - CPLEX
Exception raised:
Traceback (most recent call last):
File "/path-to-sage/local/bin/ncadoctest.py", line 1231, in
run_one_test
self.run_one_example(test, example, filename, compileflags)
File "/path-to-sage/local/bin/sagedoctest.py", line 38, in
run_one_example
OrigDocTestRunner.run_one_example(self, test, example, filename,
compileflags)
File "/path-to-sage/local/bin/ncadoctest.py", line 1172, in
run_one_example
compileflags, 1) in test.globs
File "<doctest __main__.example_9[10]>", line 1, in <module>
p.solve() # optional -
CPLEX###line 435:
sage: p.solve() # optional - CPLEX
File "mip.pyx", line 1431, in
sage.numerical.mip.MixedIntegerLinearProgram.solve
(sage/numerical/mip.c:7747)
File "cplex_backend.pyx", line 854, in
sage.numerical.backends.cplex_backend.CPLEXBackend.solve
(sage/numerical/backends/cplex_backend.c:7823)
MIPSolverException: 'CPLEX: The problem is unbounded'
**********************************************************************
File "/path-to-sage/devel/sage-
myclone/sage/numerical/backends/cplex_backend.pyx", line 437:
sage: p.get_values([x,y]) # optional - CPLEX
Expected:
[0.0, 3.0]
Got:
[2.0, 0.0]
**********************************************************************
1 items had failures:
2 of 13 in __main__.example_9
***Test Failed*** 2 failures.
For whitespace errors, see the file
/home/dcoudert/.sage//tmp/cplex_backend_17001.py
[1.2 s]
----------------------------------------------------------------------
The following tests failed:
sage -t -optional "devel/sage-
myclone/sage/numerical/backends/cplex_backend.pyx"
Total time for all tests: 1.2 seconds
}}}
I have observed that ``p.remove_constraint(0)`` removes all constraints
for the test example, hence the unbounded problem error.
{{{
sage: p = MixedIntegerLinearProgram(solver='CPLEX')
IBM ILOG License Manager: "IBM ILOG Optimization Suite for Academic
Initiative" is accessing CPLEX 12 with option(s): "e m b q ".
sage: x, y = p[0], p[1]
sage: p.add_constraint(2*x + 3*y, max = 6)
sage: p.add_constraint(3*x + 2*y, max = 6)
sage: p.set_objective(x + y + 7)
sage: p.set_integer(x); p.set_integer(y)
sage: p.show()
Maximization:
x_0 + x_1 + 7.0
Constraints:
2.0 x_0 + 3.0 x_1 <= 6.0
3.0 x_0 + 2.0 x_1 <= 6.0
Variables:
x_0 is an integer variable (min=0.0, max=+oo)
x_1 is an integer variable (min=0.0, max=+oo)
sage: p.solve()
9.0
sage: p.get_values([x,y])
[2.0, 0.0]
sage: p.remove_constraint(0)
sage: p.show()
Maximization:
x_0 + x_1 + 7.0
Constraints:
Variables:
x_0 is an integer variable (min=0.0, max=+oo)
x_1 is an integer variable (min=0.0, max=+oo)
}}}
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12823#comment:43>
Sage <http://www.sagemath.org>
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