Thank you very much!

I now understand what “alias” is used for.

Thanks!

On Tuesday, January 8, 2013 11:56:10 AM UTC-3, Renger van Nieuwkoop wrote:

Hi Lucy

Try this

Set i /i1*i3/;

alias(i,j);

parameter x(j), tot;

- Give x(j) some values:

x(j) = 1;

tot = Sum(i, sum(j$(ord(j) LE ord(i)), x(j)));

display tot;

Cheers

Renger

Modelworks

Gewerbestrasse 15

3600 Thun - Switzerland

+41 79 818 53 73

In…@modelworks.ch

blog.modelworks.ch

From: gams...@googlegroups.com [mailto:gams...@googlegroups.com] On Behalf Of Lucy N

Sent: Dienstag, 8. Januar 2013 14:56

To: gams...@googlegroups.com

Subject: Nested summation on same set

Hello, I need help for my GAMS program.

I want to do a nested summation on the same set, as follows:

sum(i in 1…n, sum(j in i…n, x_j))

I hope you understand the summation. It is a double summation where the first index (i) goes from 1 to n, and the second index goes from i to n.

In gams I defined the set 1…n as T (it is a temporal set), and I don’t know how to write the second summation.

I hope you can help me.

## Thank you very much

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