Hello Aly,
> s.t. Delivery_from_Same_Project{
> j in J, k in K, p in P, t in T: j!=k}:
> xx[j,k,p,t] ==0;
all xx with j==k are always zero. Hence it is not necessary to
define them as variables. You could define instead:
var xx{j in J, k in K, p in P, t in T: j!=k}, >= 0;
You could define that a delivery from project j to k is modeled
as a positive number and a delivery from k to j is a negative
number and define the variable xx as:
var xx{j in J, k in K, p in P, t in T: j>k};
Of cause you have to adjust the constraints using xx.
Best regards
Xypron
-------- Original-Nachricht --------
> Hi Xypron,
>
> Thanks for your reply.
>
> What do you mean by "exploiting the natural sparsity of my problem"? I
> mean, how is that done exactly in my example for instance?
>
> Aly
>
> ----- Original Message -----
> From: "glpk xypron" <[email protected]>
> To: "Aly Megahed" <[email protected]>, [email protected]
> Sent: Thursday, April 29, 2010 2:16:37 AM GMT -05:00 US/Canada Eastern
> Subject: Re: [Help-glpk] Problem in GLPK
>
> Hello Aly,
>
> > glp_malloc: no memory available
> > Error detected in file \src\glpenv05.c at line 70
> >
> > The constraint that caused that error is:
> >
> > s.t. Delivery_from_Same_Project{j in J, k in K, p in P, t in T: j!=k}:
> > xx[j,k,p,t] ==0;
> >
>
> columns that are always zero should not be defined.
>
> Instead you should exploit the natural sparsity of your
> problem to reduce the memory usage.
>
> Best regards
>
> Xypron
--
GRATIS für alle GMX-Mitglieder: Die maxdome Movie-FLAT!
Jetzt freischalten unter http://portal.gmx.net/de/go/maxdome01
_______________________________________________
Help-glpk mailing list
[email protected]
http://lists.gnu.org/mailman/listinfo/help-glpk
