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Re: [Help-glpk] Error: expression following = has invalid type


From: Raar, Dale
Subject: Re: [Help-glpk] Error: expression following = has invalid type
Date: Wed, 27 Jul 2011 18:25:34 -0400

> Hello Diego,

> 

>>  var sp{s in S, p in P} = sum{c in C} (sc[s,c] * sum{r in R} x[c,p,r]);

> 

> variables cannot be set in the declaration. Instead you can create

> a constraint, e.g.

> 

> var sp{s in S, p in P};

> 

> maximize my_objective :

>   sum{s in S, p in P} sp[s,p];

> 

> s.t. my_constraint{s in S, p in P} :

>   sp[s,p] = sum{c in C} (sc[s,c] * sum{r in R} x[c,p,r]);

> 

> If sp, sc, x are parameters, you can write:

> param sp{s in S, p in P} := sum{c in C} (sc[s,c] * sum{r in R} x[c,p,r]);

 

Xypron –

I am having a similar issue, but my original setup was using parameters.  I can not get the solver to use my primary variable with a numeric function (mod and abs in my case).  Here is a subset of my model:

 

param Def_SPk integer default 1;

 

set R;

set I;

set T;

 

param S{i in I} > 0 default Def_SPk;

 

var p{i in I, r in R, t in T} integer >=0;

 

s.t. StdPack{i in I} :

      s[i] = sum{r in R, t in T}(p[i,r,t] mod S[i])

;

 

I do not see an issue with using variable p this way – what am I missing?  Thanks,

 

Dale J. Raar • Manufacturing & Supply Chain Gentex Corporation – Zeeland, MI • 616.772.1800 x5279 • Cell: 616.402.1071

 


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