conditional summation?

[Gustavo Adolf o Pabón]

Hello Michelle Engel

En réponse à Michelle Engel <engel at mathematik.tu-darmstadt.de>:

> Hello again,
> 
> I'm trying to speed up my programm. It's complete and for small
> programms
> it works, but for large problems it's slow or it ends with error code
> 256
> (or "virtual memory exhausted :-(
> What are the main reasons for slow programms? Big number of
> Variables/Constraints? Bad order of constraints/distribution
> variables?

The main reason is that you're modeling a CSP (Constraint Satisfaction Problem)
who is a NP-Complete problem, therefore is too hard to find a efficient
algorithm  for its solution. But we can use a suitable computation model (ccp is
an example) for improving the memory and time consumption.  
.
> 
> {For 1 NrOfCars 1
>      proc{$ I}
>         {For 1 NrOfConnects 1
>  	proc{$ J}
>  	   if Connects.J.1 == Carss.I.1
>  	   then CTest.I.J =: 1
>  	   else CTest.I.J =: 0
>  	   end
>  	end
>         }
>      end
> }
> 
> Then I create constraints:
> 
> {For 1 NrOfCars 1
>      proc{$ I}
>         {FD.sumC CTest.I C '=<:' 1}
>      end
> }
> 

May be its problem can be modeled without that C_Tests variables. the use of
such vars increments too much the number of vars to solve.     
 
If you can give the problem specification we can search a best model for your
problem.


--
Ing. Gustavo Adolfo Pabon
Gerente de Proyectos - Project  Manager
Lince Technologies
(572)  6901100 ext 133
Cali - Colombia - South America

URL:   http://atlas.puj.edu.co/~gpabon/
EMAIL: gpabon at atlas.puj.edu.co

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