Re: [Help-glpk] Problem

[glpk xypron]

Hello Ramón,

> if my model is right, it has to give me the same results 
> no matter the insertion order
a MIP problem may have multiple solutions with the same value
of the objective function. In this case any solution with
the minimum objective function value is correct.

Did you get different objective function values for different
insertion orders?

You can find an example code for solving cutting stock problems
with GLPK at http://code.google.com/p/cspsol/

> Congratulations, I love glpk.jar.
You seem to refer to the GLPK-Java interface published on
bjoern.dapnet.de/glpk/ This interface has not beeen maintained
for some time and does not support the current GLPK API.

Consider using GLPK for Java available at 
http://glpk-java.sourceforge.net

Best regards

Xypron



-------- Original-Nachricht --------
> Datum: Fri, 3 Sep 2010 22:01:46 -0500
> Von: "Ramón Andrés Vega Villa" <address@hidden>
> An: address@hidden
> CC: juan_f_diaz <address@hidden>
> Betreff: [Help-glpk] Problem

> Hi.
> 
> I have a problem. I am using simplex and MIP classes in Cutting Stock
> Problem but it doesn't use all the possibilities.
> 
> We know that the INPUT data of the Cutting Stock Problem in divided in
> 
>    - What we need (pieces we have to cut or result pieces)
>    - What we have or Stock (commercial lengths or retail pieces of
> previous
>    cuts)
> 
> For example, if I have 6 comercial lengths of 600 cms, 3 of 300 cms, and a
> retail piece of 170 cms and I insert them in my model or the matrix in the
> following way... 600,300,170,600,300,600,300,600,600,600, it consumes or
> cut
> the comercial pieces in order and does not iterate in all the comercial
> lengths not guaranting the best way
> of minimizing left over or retail pieces. In other words, if my model is
> wright, it has to give me the same results no matter the insertion order
> and
> this is not happening.
> 
> It works with only one comercial length, but it is not fulfilling my
> requirements.
> 
> Any advise?
> 
> Congratulations, I love glpk.jar.
> 
> Thank you.

-- 
GMX DSL SOMMER-SPECIAL: Surf & Phone Flat 16.000 für nur 19,99 Euro/mtl.!*
http://portal.gmx.net/de/go/dsl