#13148: make LP return the number of variables
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Reporter: dimpase | Owner: ncohen
Type: enhancement | Status: needs_work
Priority: major | Milestone: sage-5.2
Component: linear programming | Resolution:
Keywords: | Work issues:
Report Upstream: N/A | Reviewers:
Authors: | Merged in:
Dependencies: | Stopgaps:
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Comment (by dimpase):
Replying to [comment:2 ncohen]:
> -_-
>
> Ahem... With Gurobi installed the doctests do not pass, because of their
stupid way of storing double inequalities :
> {{{
> sage: p = MixedIntegerLinearProgram()
> sage: p.add_constraint(p[0] - p[2], min = 1, max = 4)
> sage: p.number_of_variables()
> 3
> sage: p.show()
> Maximization:
>
> Constraints:
> R0: 4.0 <= x_0 - x_1 + RgR0 <= 4.0
> Variables:
> x_0 is a continuous variable (min=0.0, max=+oo)
> x_1 is a continuous variable (min=0.0, max=+oo)
> RgR0 is a continuous variable (min=0.0, max=3.0)
> }}}
as far as I am concerned this is an LP with 3 variables, not 2.
So my code is right :–)
(well, you don't have means to control that RgR0, so what?)
When you construct the usual dual of such an LP, you'll end up with
a different dual.
>
> Of course I expect that your code works with any other solver `^^;`
>
> Could you change the first constraint so that it is a "simple"
inequality (with not both an upper and lower bound) ?
hmm, I don't see what you mean here.
>
> Your patch also needs some commit message. And I do not know if there is
any rule about patches filenames ending with a .patch, but we will find
out soon `:-)`
>
> Sorry about this Gurobi ugliness `:-p`
>
> Nathann
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/13148#comment:3>
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