Upper bound summation GAMS

[inma.moll]

Hi,

Can I put an upper bound summation?
for example:
sum(i, start i=1 to n) * prod(j, start j=1=start to i) Aj= A1 + A1*A2
+ A1*A2*A3 +.... +A2*A2*...*An

[zahra adel]

Well, first of all in GAMS sets are different from numbers. When you define "i" as a set, you can never use an expression like "i<3" or "i<n". Instead you may use "ord(i)" (Ord(i) returns the number of the element being referenced relative to the total number of elements in the set) as a counter.

Besides, You can use conditional structure for upper or lower bounds. for example, instead of
"sum(i, start i=1 to n,...)" you may write "sum( i$( ord(i)<n) ,...)" which means:" sum over set i if ord(i) is less than n".

I hope it helps you.

Zahra.

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From: inma.moll <inma...@yahoo.es>
To: gamsworld <gams...@googlegroups.com>
Sent: Sun, April 24, 2011 8:24:25 PM
Subject: Upper bound summation GAMS

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