mpstrans.gms : MPS file for transportation problem

**Description**

PUT statements are used to generate the linear programming matrix of the problem TRNSPORT (SEQ=1) in standard industry format, the MPS file. The first part of this file is taken from the model TRNSPORT. This is not to suggest writing MPS files with GAMS but a way to demonstrate the use of PUT statements.

**Reference**

- Dantzig, G B, Chapter 3.3. In Linear Programming and Extensions. Princeton University Press, Princeton, New Jersey, 1963.

**Small Model of Type :** GAMS

**Category :** GAMS Model library

**Main file :** mpstrans.gms

```
$title MPS file for Transportation Problem (MPSTRANS,SEQ=104)
$onText
PUT statements are used to generate the linear programming
matrix of the problem TRNSPORT (SEQ=1) in standard industry
format, the MPS file. The first part of this file is taken from
the model TRNSPORT. This is not to suggest writing MPS files with
GAMS but a way to demonstrate the use of PUT statements.
Dantzig, G B, Chapter 3.3. In Linear Programming and Extensions.
Princeton University Press, Princeton, New Jersey, 1963.
Keywords: mathematical programming system, linear programming, transportation
problem, scheduling
$offText
$eolCom //
Set
i 'canning plants' / seattle, san-diego /
j 'markets' / new-york, chicago, topeka /;
Parameter
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;
File mps 'mps input file';
mps.pc = 2; // set page control to stream format
mps.case = 1; // upper case file
mps.nd = 0; // default decimal places are set to zero
mps.nw = 0; // default numeric field width is zero - variable length
* two different ways to form mps names are demonstrated, using
* the ordinal index values and a second one, using the label name
* use ordinal values to form mps names
put mps 'name' @15 'trnsport'
/ 'rows'
/ ' n' @5 'cost';
loop(i, put / ' l' @5 'sup' ord(i));
loop(j, put / ' g' @5 'dem' ord(j));
put / 'columns';
loop((i,j),
put / @5 'x' ord(i) ord(j) @15 'cost' @25 c(i,j):12:5
/ @5 'x' ord(i) ord(j) @15 'sup' ord(i) @25 1.0 :12:5
/ @5 'x' ord(i) ord(j) @15 'dem' ord(j) @25 1.0 :12:5;
);
put / 'rhs';
loop(i, put / @5 'rhs' @15 'sup' ord(i) @25 a(i):12:5);
loop(j, put / @5 'rhs' @15 'dem' ord(j) @25 b(j):12:5);
put / 'endata';
* use first two characters of label to form names
mps.nd = 5; // default decimals are 5
mps.nw = 12; // numeric field width is 12
mps.lw = 2; // label field width is 2 - take only first two characters
put / 'name' @15 'trnsx'
/ 'rows'
/ ' n' @5 'c' ;
loop(i, put / ' l' @5 's' i.tl;);
loop(j, put / ' g' @5 'd..' j.tl;);
put / 'columns';
loop((i,j),
put / @5 'x' i.tl j.tl @15 'c' @25 c(i,j)
/ @5 'x' i.tl j.tl @15 's' i.tl @25 1.0
/ @5 'x' i.tl j.tl @15 'd..' j.tl @25 1.0 ;
);
put / 'rhs';
loop(i, put / @5 'rhs' @15 's' i.tl @25 a(i););
loop(j, put / @5 'rhs' @15 'd..' j.tl @25 b(j););
put / 'endata';
```