On Sat, Jun 30, 2012 at 04:34:19AM +1200, Robbie Morrison wrote:
>
> ------------------------------------------------------------
> To: Edd Barrett <vex...@gmail.com>
> Subject: Re: [Help-glpk] glpsol, arbitrary precision and large numbers
> Message-ID: <20120629094235.gl11...@edd-i386.kent.ac.uk>
> From: Edd Barrett <vex...@gmail.com>
> Date: Fri, 29 Jun 2012 10:42:35 +0100
> ------------------------------------------------------------
>
> > On Wed, Jun 27, 2012 at 01:03:35PM +0100, Edd Barrett wrote:
> >
> >> Which is false, so under this assignment the system
> >> in infeasible. The solver should have either tried a
> >> different assignment of either variables, or if it
> >> could not, then it should have reported the problem
> >> infeasible? Right?
> >
> > Any thoughts on this? I am keen to figure out what went
> > wrong here.
> >
> > Cheers
> >
> > --
> > Best Regards
> > Edd Barrett
> >
> > http://www.theunixzoo.co.uk
>
> Hi Edd
>
> No idea what the underlying problem is but here are
> some debugging suggestions:
>
> * try formulating a minimum reproducible case and
> circulate that
>
> * check the KKT conditions if appropriate
>
>
> http://en.wikibooks.org/wiki/GLPK/Solution_information#Karush-Kuhn-Tucker_optimality_conditions
Ah, I am failing the KKT.PB check. From the .sol file I attached in my earlier
mail:
---8<---
Integer feasibility conditions:
KKT.PE: max.abs.err = 0.00e+00 on row 0
max.rel.err = 0.00e+00 on row 0
High quality
KKT.PB: max.abs.err = 5.00e+00 on row 15
max.rel.err = 1.00e+00 on row 15
SOLUTION IS INFEASIBLE
---8<---
So I guess the result is unreliable. I will have to read into this more.
>
> * export your MathProg model in MPS format and try
> solving that with GLPSOL or with other solvers
>
> http://en.wikibooks.org/wiki/GLPK/Interoperability#MPS_free_format
I have already tried lpsolve. Today I was looking into using the PPL solver:
http://bugseng.com/products/ppl
Cheers for everyone's help.
--
Best Regards
Edd Barrett
http://www.theunixzoo.co.uk
_______________________________________________
Help-glpk mailing list
Help-glpk@gnu.org
https://lists.gnu.org/mailman/listinfo/help-glpk
