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gams:counting_the_number_of_equations_generated_by_a_specific_constraint [2007/08/09 15:56] (current)
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 +====== Counting the Number of Equations generated by a specific Constraint ======
 +
 +//Q: I wonder if there is a nice way to count the number of the equation that is is related to a specific constraint. For example, a gams expression that is://
 +
 +    demand(j) ..   ​sum(i,​ x(i,​j)) ​ =g=  b(j) ; 
 +
 +//How can I count the number of equation generated by that equation? Is there any suffix or index I can refer to?//
 +
 +If you use the limrow = 1 option, then the output of your gams model will include the first instance of every equation you have defined and include a message indicating the number of skipped rows also generated:
 +<​code>​
 +---- demand ​ =G=  satisfy demand at market j
 +
 +demand(new-york).. ​ x(seattle,​new-york) + x(san-diego,​new-york) =G= 325 ;
 +     
 +      (LHS = 0, INFES = 325 ***)
 +     
 +REMAINING 2 ENTRIES SKIPPED
 +</​code> ​
 +
 +Thus the constraint ''​demand(j)''​ generates three equations.
 +
 +Another approach is to use the results of the ''​profile''​ option to get the number of generated equations. Below is an example, which writes the collected information of the trnsport model into a file ''​eq.txt'':​
 +<​code>​
 +$call '​gamslib trnsport'​
 +option limrow=1,​limcol=0,​ profile=1;
 +$include trnsport.gms
 +*  get number of equations from profile
 +execute 'grep -i secs %system.ofile% |grep "​EQUATION"​ >​eq.txt'​
 +</​code>​
 +The last entry of each line in ''​eq.txt''​ tells you the number of generated equations:
 +<​code>​
 +  74  execute 'grep -i secs C:​\temp\xxx\t2.lst |grep "​EQUATION"​ >​eq.txt'​
 +----     61 EQUATION ​  ​cost ​         0.000     0.000 SECS      4 Mb      1
 +----     63 EQUATION ​  ​supply ​       0.000     0.000 SECS      4 Mb      2
 +----     65 EQUATION ​  ​demand ​       0.000     0.000 SECS      4 Mb      3
 +</​code>​
 +
 +
  
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