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# A TRANSPORTATION PROBLEM
#
# This problem finds a least cost shipping schedule that meets
# requirements at markets and supplies at factories.
#
# References:
# Dantzig G B, "Linear Programming and Extensions."
# Princeton University Press, Princeton, New Jersey, 1963,
# Chapter 3-3.
set I;
/* canning plants */
set J;
/* markets */
param a{i in I};
/* capacity of plant i in cases */
param b{j in J};
/* demand at market j in cases */
param d{i in I, j in J};
/* distance in thousands of miles */
param f;
/* freight in dollars per case per thousand miles */
param c{i in I, j in J} := f * d[i,j] / 1000;
/* transport cost in thousands of dollars per case */
var x{i in I, j in J} >= 0;
/* shipment quantities in cases */
minimize cost: sum{i in I, j in J} c[i,j] * x[i,j];
/* total transportation costs in thousands of dollars */
s.t. supply{i in I}: sum{j in J} x[i,j] <= a[i];
/* observe supply limit at plant i */
s.t. demand{j in J}: sum{i in I} x[i,j] >= b[j];
/* satisfy demand at market j */
data;
set I := Seattle San-Diego;
set J := New-York Chicago Topeka;
param a := Seattle 350
San-Diego 600;
param b := New-York 325
Chicago 300
Topeka 275;
param d : New-York Chicago Topeka :=
Seattle 2.5 1.7 1.8
San-Diego 2.5 1.8 1.4 ;
param f := 90;
end;
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