User Tools

Site Tools


gams:the_for_statement

Differences

This shows you the differences between two versions of the page.

Link to this comparison view

gams:the_for_statement [2007/02/02 16:48] (current)
Line 1: Line 1:
 +====== The FOR statement ======
 +The FOR statement is used in order to loop over a block of 
 +statements. ​
  
 +Syntax
 +
 +The syntax is: 
 +
 +     FOR ( i = start TO|DOWNTO end [By incr],
 +            statements;
 +           );
 +
 +Warning: One cannot make declarations or define equations inside ​
 +         a FOR statement. ​
 +
 +
 +Example 1
 +
 +One can use FOR statements to control the SOLVE statement. For instance,
 +consider the following bit of GAMS code that randomly searches for a 
 +global optimum of a nonconvex model: ​
 +
 +     ​scalar count ;
 +     for (i = 1 to 1000,
 +             ​x.l(j) = uniform(0,​1) ;
 +             ​option bratio = 1 ;
 +             solve ml using nlp minimizing obj ;
 +             if (obj.l le globmin,
 +                 ​globmin = obj.l ;
 +                 ​globinit(j) = x.l(j) ;
 +                ) ;
 +           ) ;
 +
 +In this example, a non-convex model is solved from 1000 random ​
 +starting points, and the global solution is tracked. ​
 +
 +Example 2
 +
 +The following GAMS code is illegal since one cannot define equations ​
 +inside a FOR statement. ​
 +
 +     For (s = 1 to 5 by 1,
 +              eq.. sum(i,x(i)) =g= 2 ;
 +           );
 +
 +Example 3
 +
 +The following GAMS code is illegal since one cannot make declarations ​
 +inside a FOR statement. ​
 +
 +     For (s=1 to 5 by 1,
 +              scalar y ; y = 5 ;
 +            );
IMPRESSUM / LEGAL NOTICEPRIVACY POLICY gams/the_for_statement.txt ยท Last modified: 2007/02/02 16:48 (external edit)