#12823: Allow constants for objective function in MixedIntegerLinearProgram
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Reporter: john_perry | Owner: ncohen
Type: PLEASE CHANGE | Status: new
Priority: major | Milestone: sage-5.0
Component: linear programming | Keywords: solver objective
Work issues: | Report Upstream: N/A
Reviewers: | Authors:
Merged in: | Dependencies:
Stopgaps: |
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This is a bug.
{{{
sage: lp = MixedIntegerLinearProgram()
sage: x, y = lp[0], lp[1]
sage: lp.add_constraint(2*x + 3*y <= 6)
sage: lp.add_constraint(3*x + 2*y <= 6)
sage: lp.set_objective(x + y + 7)
sage: lp.set_integer(x); lp.set_integer(y)
sage: lp.solve()
2.0
}}}
The correct value ought to be '''9''', not '''2'''. The problem is this
line in the `set_objective()` method of `mip.pyx`:
{{{
f.pop(-1,0)
}}}
John Perry will create a patch for GLPK and CBC; Nathann Cohen will create
a patch for Gurobi and CPLEX.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12823>
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