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gams-math

GAMS- uncontrolled set entered as constant

Consider the following problem in GAMS. I have two disjoint sets: iand j. These are proper subsets of a subset k, where the union of i and j exactly equal the elements of k. I wish to construct a new variable X(k) (for the proper subset), that is a concatenation of A(i) and B(j). Intuitively, I wish to declare:

parameter 
X(k);

X(k)=A(i)+B(j);

Of course, this operation is not legal as i and j do not conform. But the idea is to take the values from A(i) for the i elements of X(k), and the rest to be taken from B(j). Any help on this is much appreciated!!

Solution

  • This sounds like a perfect example for an implicit set definition. So, you can do the following:

    Set
   k
   i(k<)    / i1*i3  /
$onMulti
   j(k<)    / j1*j3  /;
   
parameter X(k);

    Check this for more information:

    https://www.gams.com/32/docs/UG_SetDefinition.html#UG_SetDefinition_ImplicitSetDefinition