Description

In this test we check how a solver behaves when there is only
one objective variable in one free equation.  Different tests
are performed applying different directions of optimization.

Contributor: Steve Dirkse

Small Model of Type : LP

Category : GAMS Test library

Main file : lp11.gms

$title 'Simple test on one =n= equation' (LP11,SEQ=251)

$ontext
In this test we check how a solver behaves when there is only
one objective variable in one free equation.  Different tests
are performed applying different directions of optimization.

Contributor: Steve Dirkse
$offtext

$if not set MTYPE     $set MTYPE lp
$if not set SKIPUNBND $set SKIPUNBND 0

variable obj;

equations e;

model m / e /;

e.. obj =n= 1;

scalar tol / 1e-6 /;
scalar skipUnBnd / %SKIPUNBND% /;

if {not skipUnBnd,
  solve m max obj us %MTYPE%;
  abort$[(m.solvestat <> %solvestat.NormalCompletion% or (m.modelstat <> %modelstat.Unbounded%)
         and (m.modelstat <> %modelstat.Unbounded-NoSolution%))] 'wrong status codes';

  solve m min obj us %MTYPE%;
  abort$[(m.solvestat <> %solvestat.NormalCompletion% or (m.modelstat <> %modelstat.Unbounded%)
         and (m.modelstat <> %modelstat.Unbounded-NoSolution%))] 'wrong status codes';
};

obj.lo = -1000; obj.up = 1000;

solve m max obj us %MTYPE%;
  abort$(m.solvestat <> %solvestat.NormalCompletion% or m.modelstat <> %modelstat.Optimal%) 'wrong status codes';
  abort$(m.numnopt  <> 0)              '    NONOPT flags set';
  abort$(m.numinfes <> 0)              'INFEASIBLE flags set';
  abort$(abs(m.objval - 1000) > tol)   'bad m.objval';
  abort$(abs(e.l - 999)  > tol)        'bad equation level';
  abort$(abs(e.m - 0)    > tol)        'bad equation marginal';
  abort$(abs(obj.l - 1000)     > tol)  'bad variable level';
  abort$(abs(obj.m - 1)        > tol)  'bad variable marginal';

solve m min obj us %MTYPE%;
  abort$(m.solvestat <> %solvestat.NormalCompletion% or m.modelstat <> %modelstat.Optimal%) 'wrong status codes';
  abort$(m.numnopt  <> 0)              '    NONOPT flags set';
  abort$(m.numinfes <> 0)              'INFEASIBLE flags set';
  abort$(abs(m.objval + 1000) > tol)   'bad m.objval';
  abort$(abs(e.l + 1001) > tol)        'bad equation level';
  abort$(abs(e.m - 0)    > tol)        'bad equation marginal';
  abort$(abs(obj.l + 1000)     > tol)  'bad variable level';
  abort$(abs(obj.m - 1)        > tol)  'bad variable marginal';