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Purpose: To provide a GAMS formulation for the collection
of Gupta Problems

Reference: Branch and bound experiments in convex nonlinear
integer programming, Management Science, 1533-1546, 31, 1985.

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Variables  i1,i2,x3,objvar;

Positive Variables x3;

Integer Variables i1,i2;

Equations  e1,e2,e3,e4;


e1.. 420.169404664517*sqrt(900 + sqr(i1)) - x3*i1*i2 =E= 0;

e2..  - x3 =G= -100;

e3.. 296087.631843*(0.01 + 0.0625*sqr(i2))/(7200 + sqr(i1)) - x3 =G= 0;

e4..  - 0.04712385*i2*sqrt(900 + sqr(i1)) + objvar =E= 0;

* set non default bounds

i1.up = 200; 
i2.up = 200; 
x3.up = 100; 

* set non default levels

i1.l = 100; 
i2.l = 100; 
x3.l = 100; 

* set non default marginals


Model m / all /;

m.limrow=0; m.limcol=0;

$if NOT '%gams.u1%' == '' $include '%gams.u1%'

Solve m using MINLP minimizing objvar;