OPTMODEL - Fix stement

[Prabhavanth]

Could anyone please explain what difference does a fix statement make in the optmodel procedure?

Thanks in advance.

[user24feb]

It sets/fixes a variable to a certain value.

Exactly as in:

 proc optmodel;
      var x{1..10};
      fix x = 0;
      fix x[10] = 1;

From: http://support.sas.com/documentation/cdl/en/ormpug/66851/HTML/default/viewer.htm#ormpug_optmodel_syn...

[Prabhavanth]

Thanks for the reply.

But, what's the diffrence between the following two programs?

1)

Proc optmodel;

var x;

x=2;

put x=;

quit;

2)

Proc optmodel;

var x;

fix x=2;

put x=;

quit;

[user24feb · Accepted solution]

Initial value vs. actually fixed value. Compare results.

Proc optmodel;
var x;
x=2;
con con: x<=10;
max obj=x;
solve;
put x=;
quit;

Proc optmodel;
var x;
fix x=2;
con con: x<=10;
max obj=x;
solve;
put x=;
quit;

[Prabhavanth]

It now explains. Thanks a lot.