gams: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:

---- 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

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`

:

$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'

The last entry of each line in `eq.txt`

tells you the number of generated equations:

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

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gams/counting_the_number_of_equations_generated_by_a_specific_constraint.txt · Last modified: 2007/08/09 15:56 (external edit)