Hi

I think, but I am not sure at all, because I don’t know how large your problem is, this may help :

First:

ALIAS (t,tt);

Second define a parameter like x(tt) ,equal to zero.

then for the specific element of set " tt " , like " t’ “, that you want a(” t’ ") takes value, do :

x("t’ ") =1;

then modify your equation to this:

c(t) (ord(t) eq 1) = b(t) (ord(t) eq 1) - ( SUM(tt, x(tt) * a(tt) );

as for all tt, xx(tt) is zero except for tt = 3, you will have desire equation :

c(“1”)=b(“1”)-a(“3”)

.

Good Luck

On Fri, Sep 16, 2011 at 5:15 AM, Graeme Doole wrote:

Hi

I have a problem in a large and complex model that regards subtraction

of two parameters. I have illustrated the problem in a very simple

program described below, so I can show my problem more clearly. The

complete program is:

set t/1*3/;

parameter a(t)/1=0,2=0,3=1/;

parameter b(t)/1=1,2=0,3=0/;

parameter c(t);

c(t)(ord(t) eq 1)=b(t)(ord(t) eq 1)-a(t)$(ord(t) eq 3);

display a,b,c;

I wish c(“1”)=b(“1”)-a(“3”), or 0=1-1. However, the above code gives

me an error in that c(“1”)=1. I understand there is a problem in my

use of the ord statement. However, I am just wondering how this should

be coded to ensure I get the correct result.

Thank you for any help.

Babak Saleck Pay

M.Sc

Socio-Economic System Engineering

Group of Industrial Engineering

University of Tehran

Tehran,Iran

–

To post to this group, send email to gamsworld@googlegroups.com.

To unsubscribe from this group, send email to gamsworld+unsubscribe@googlegroups.com.

For more options, visit this group at http://groups.google.com/group/gamsworld?hl=en.