Description

In this test we check infeasible and unbounded conditions

Small Model of Type : LP

Category : GAMS Test library

Main file : lp04.gms

$title Tests basic modelstat codes (LP04,SEQ=69)

$onText
In this test we check infeasible and unbounded conditions
$offText

$if not set SKIPUNBND $set SKIPUNBND 0
scalar skipUnBnd / %SKIPUNBND% /;

  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    NA  /

       b(j)  demand at market j in cases
         /    new-york    325
              chicago     300
              topeka      275  / ;

  Table c(i,j)  distance in thousands of miles
                    new-york       chicago      topeka
      seattle           NA           1.7          1.8
      san-diego        3.5           2.8          1.4  ;

  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 lp04 /all/ ;

option limcol=0,limrow=0;


c('seattle','new-york') = 2.5; a('san-diego') = 600;
option clear=x,clear=z,clear=cost,clear=supply,clear=demand;
Solve lp04 using lp minimizing z ;
abort$( lp04.solvestat <> %solveStat.normalCompletion% or lp04.modelstat <> %modelStat.optimal%) 'wrong status codes';
abort$( lp04.numnopt  <> 0 ) 'bad numnopt';
abort$( lp04.numinfes <> 0 ) 'bad numinfes';

c('seattle','new-york') = 2.5; a('san-diego') = 500;
option clear=x,clear=z,clear=cost,clear=supply,clear=demand;
Solve lp04 using lp minimizing z ;
abort$( lp04.solvestat <> %solveStat.normalCompletion% or (lp04.modelstat <> %modelStat.infeasible% and lp04.modelstat <> %modelStat.infeasibleNoSolution%)) 'wrong status codes';
abort$( lp04.numnopt  <> 0 ) 'bad numnopt';
abort$( lp04.numinfes  = 0 ) 'bad numinfes';

c('seattle','new-york') =  2.5; a('seattle') = inf;
option clear=x,clear=z,clear=cost,clear=supply,clear=demand;
Solve lp04 using lp minimizing z ;
abort$( lp04.solvestat <> %solveStat.normalCompletion% or lp04.modelstat <> %modelStat.optimal%) 'wrong status codes';
abort$( lp04.numnopt  <> 0 ) 'bad numnopt';
abort$( lp04.numinfes <> 0 ) 'bad numinfes';

c('seattle','new-york') = -2.5; a('seattle') = inf;
option clear=x,clear=z,clear=cost,clear=supply,clear=demand;
if {not skipUnBnd,
  Solve lp04 using lp minimizing z ;
  abort$( lp04.solvestat <> %solveStat.normalCompletion% or (lp04.modelstat <> %modelStat.unbounded% and lp04.modelstat <> %modelStat.unboundedNoSolution%)) 'wrong status codes';
  if {(lp04.modelstat <> %modelStat.unbounded%),
    abort$( lp04.numinfes = 0 ) 'bad numinfes';
  };
};