Hi,

In the “A GAMS Tutorial by Richard E. Rosenthal” (https://www.gams.com/latest/docs/UG_Tutorial.html), I’m trying to run the model several times in a sequential way in order to see the influence of changing same SCALAR/PARAMETERS in each model run

Problem 1

What I want to do is to run the model several times with diferent “f” (Scalar f freight in dollars per case per thousand miles /90/) to see the impact (sensibility) on the model results when I change “f” from 90 to other value (30, 40 50, … , 130, 140, 150).

Problem 2

Very similar to the first one. The only difference is that I want to try the Seattle capacity (350 cases) to 250,300,400 and 450 and see the impact on the optimization results

Bottom line, I want (if possible) to run the model several times with some differences in the SCALAR and/or in the PARAMETERS

Does anyone knows how to do this? (if possible)

Thanks

Paulo

$title a transportation model

Sets

i canning plants / seattle, san-diego /

j markets / new-york, chicago, topeka / ;

Parameters

a(i) capacity of plant i in cases

/ seattle 350

san-diego 600 /

b(j) demand at market j in cases

/ new-york 325

chicago 300

topeka 275 / ;

Table d(i,j) distance in thousands of miles

new-york chicago topeka

seattle 2.5 1.7 1.8

san-diego 2.5 1.8 1.4 ;

Scalar f freight in dollars per case per thousand miles /90/ ;

Parameter c(i,j) transport cost in thousands of dollars per case ;

c(i,j) = f * d(i,j) / 1000 ;

Variables

x(i,j) shipment quantities in cases

z total transportation costs in thousands of dollars ;

Positive Variable x ;

Equations

cost define objective function

supply(i) observe supply limit at plant i

demand(j) satisfy demand at market j ;

cost … z =e= sum((i,j), c(i,j)*x(i,j)) ;

supply(i) … sum(j, x(i,j)) =l= a(i) ;

demand(j) … sum(i, x(i,j)) =g= b(j) ;

Model transport /all/ ;

Solve transport using lp minimizing z ;

Display x.l, x.m;