Refer to Special element of a set

GAMS
1

Hi,
Consider I have defined set i as /5,7,8,3,2,9/ in Gams and I want to define sub(i) such that contains the first element of i and define sub2(i) such that includes the last element of i. How shoud I do that?
It is notable that the set i is imported to Gams and I don’t know its element in advance.

2

First make sure you get the order of i you expect by “display i”; Then you can get the first and last element like this

set iFirst(i), iLast(i);
iFirst(i) = i.first;
iLast(i) = i.last;
display i,iFirst,iLast;

-Michael

3

Thanks for your help.