#18764: Add glp_exact to Sage's GLPK bindings
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Reporter: mkoeppe | Owner:
Type: enhancement | Status: new
Priority: minor | Milestone: sage-6.8
Component: numerical | Resolution:
Keywords: lp | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Comment (by mkoeppe):
Hi Dima,
Replying to [comment:1 dimpase]:
> copying from a comment on another ticket:
>
> I don't think using non-public non-documented features is a good idea.
Next version would break them, and we'd be stuck with maintaining a
fork...
> Perhaps we have to find a way first to make GLPK folks finally address
the public need of making these things public?
I share your concern about the non-public functions, which is valid for
the other ticket (#18765), but *not* for this ticket.
glp_exact is a documented API function.
There's just no way to feed the problem using exact data, or to retrieve
the solution using exact data.
However, if the problem can be expressed using small integers (<= 53 bits)
that are represented exactly by double floats, then the rational
reconstruction that GLPK does should be exact. The Sage code could refuse,
or warn, if this is violated.
And we can access the combinatorial information about the basis on the
Sage side and compute the basic solution using exact arithmetic.
--
Ticket URL: <http://trac.sagemath.org/ticket/18764#comment:2>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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