#18765: Add Cython wrappers for GLPK's interface glpssx.h (exact rational
simplex)
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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 dimpase):
Replying to [comment:2 mkoeppe]:
> Replying to [comment:1 dimpase]:
> > I don't understand how using standard glp_ functions would not lead to
loss of precision, rendering subsequent exact computations meaningless.
Are you doing to watch for the numerical troubles in the double-float
phase?
>
> One just uses double float to navigate to some basis that's hopefully
close to an optimal one.
more realistic scenario is "try to use double floats" to navigate to
"something that hopefully is close enough to a basis".
This is what I learnt while trying to solve LPs which are too hard for
floating point simplex (implemented in CPLEX, say). Typical scenario:
* CPLEX: your problem is infeasible
* me: OK, give me a certificate of this
* CPLEX: oops, I cannot :(
--
Ticket URL: <http://trac.sagemath.org/ticket/18765#comment:3>
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