Re: [Help-glpk] Switching Indexes within an expression (Inline)

[xypron]

Hello Thilo,


Thilo Bohr wrote:
> 
> Given are the following Parameter:
> 
> param x {b in B, a in A, c in C};
> param y {b in B, a in A, c in C};
> param z {b in B, a in A, c in C} :
>    (x[b, a, c] + y[b, a, c]);
> param result {a in A, b in B, c in C} : z[a, b, c];
> 
> As you can see, the result has the Indexes a and b switched.
> 
> Is there a construct that allows me define the result Parameter without 
> the need of the z Parameter?
> 
> I.e. is it possible to switch the indexes a und b "inline" (i.e. within 
> the expression)?
> 
> The following does not work:
> 
> param result {a in A, b in B, c in C} :
>    (x[b, a, c] + y[b, a, c])[a, b, c];
> 

Your statements concerning z are only valid, if A = B.
For the correct syntax without z see r2 in example below.
For a correct transposition look at r3.

Best regards

Xypron



set A;
set C;

param x {b in A, a in A, c in C} := Uniform(0,1);
param y {b in A, a in A, c in C} := Uniform(0,1);
param z {b in A, a in A, c in C} := x[b, a, c] + y[b, a, c];
# the fowllowing does not cause as transposition
param r1 {a in A, b in A, c in C} := z[a, b, c];
param r2 {a in A, b in A, c in C} := x[a, b, c] + y[a, b, c];
# now lets do a proper transposition
param r3 {a in A, b in A, c in C} := x[b, a, c] + y[b, a, c];

printf "Please, check the following:\n";
printf "[%2s,%2s,%2s]: %6s + %6s = %6s = %6s ?= %6s\n", 
  "", "", "", "x", "y", "r1", "r2", "r3";
for {a in A, b in A, c in C}
  printf "[%2s,%2s,%2s]: %6.4f + %6.4f = %6.4f = %6.4f ?= %6.4f\n", 
    a, b, c, x[a,b,c], y[a,b,c], r1[a,b,c], r2[a,b,c], r3[a,b,c];

data;
set A := a1 a2;
set C := c1 c2;
end;

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