mpstrans.gms : MPS file for transportation problem
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
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$Title MPS file for transportation problem (MPSTRANS,SEQ=104)
$ Eolcom !
$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.
$Offtext
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 ;
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 firts 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' ;
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