Re: [Help-glpk] symbolic parameter in set

[Andrew Makhorin]

> In version 4.8 there is a nice example: maxflow.mod
>  
> regarding this example, how does one declare and assign a 
> symbolic (string) parameter within the Arcs set?
>  
> i.e., I would like to assign a 'name' parameter to Arcs:
>  
> param n, integer, >= 2;
> /* number of nodes */
>  
> set Nodes, default {1..n};
> /* set of nodes */
>  
> set Arcs, within Nodes cross Nodes;
> /* set of arcs */
>  
> param capacity {(i,j) in Arcs}, > 0;
> /* capacity[i,j] is capacity of arc (i,j) */
>  
> param name, symbolic, {(i,j) in Arcs};
> .....
>  
> data;
>  
> param : Arcs : name  capacity :=
>        1 2   arc1  14
>        1 4   arc2  23
>        ....;
> 
>  
> with the line 23 as: param name, symbolic, {(i,j) in Arcs};
> I get: 
> Reading model section from maxflow.mod...
> maxflow.mod:23: syntax error in parameter statement
> Context: ...city { ( i , j ) in Arcs } , > 0 ; param name , symbolic , {
> Model processing error
>  

Your syntax is wrong. The correct syntax is the following:

param name{(i,j) in Arcs} symbolic;

(The comma preceding 'symbolic' is optional and may be omitted.)