* AMPL Model by Hande Y. Benson
*
* Copyright (C) 2001 Princeton University
* All Rights Reserved
*
* Permission to use, copy, modify, and distribute this software and
* its documentation for any purpose and without fee is hereby
* granted, provided that the above copyright notice appear in all
* copies and that the copyright notice and this
* permission notice appear in all supporting documentation.

*   Source: problem MINLEN in
*   Vasko and Stott
*   "Optimizing continuous caster product dimensions:
*    an example of a nonlinear design problem in the steel industry"
*   SIAM Review, Vol 37 No, 1 pp.82-84, 1995

*   SIF input: A.R. Conn April 1995

*   classification LOR2-RN-5-4

parameter mintph  ;  mintph   =  45.0;
parameter minthick;  minthick =   7.0;
parameter minarea ;  minarea  = 200.0;
parameter maxarea ;  maxarea  = 250.0;
parameter maxaspr ;  maxaspr  =   2.0;
parameter     k   ;      k    =   1.0;

Variable    thick, wid,len, tph,ipm, f ;

Equation Eq_1, Eq_2, Eq_3, Eq_4, Eq_5, Def_obj ;

Eq_1..        117.370892*tph/(wid*thick)-ipm =e= 0.0;
Eq_2..         sqr(thick)*ipm/48.0-len =e= 0.0;
Eq_3..         wid/thick =l= maxaspr;
Eq_4..         thick*wid - minarea =l= maxarea-minarea;
Eq_5..         thick*wid - minarea =g= 0              ;

Def_obj.. f=e= len ;

thick.lo  = minthick;
wid.lo    = 0.000001;
len.lo    = 0.0     ;
tph.lo    = mintph  ;
ipm.lo    = 0.0     ;

thick.l   = 0.5     ;
wid.l     = 0.5     ;
len.l     = 0.5     ;
tph.l     = 0.5     ;
ipm.l     = 0.5     ;

Model csfi2 /all/;

Solve csfi2 using nlp minimize f;

display f.l;
display thick.l;
display wid.l  ;
display len.l  ;
display tph.l  ;
display ipm.l  ;