$title Pareto optimal front determination

$onText
For more details please refer to Chapter 2 (Gcode2.16), of the following book:
Soroudi, Alireza. Power System Optimization Modeling in GAMS. Springer, 2017.
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Model type: NLP
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Contributed by
Dr. Alireza Soroudi
IEEE Senior Member
email: alireza.soroudi@gmail.com
We do request that publications derived from the use of the developed GAMS code
explicitly acknowledge that fact by citing
Soroudi, Alireza. Power System Optimization Modeling in GAMS. Springer, 2017.
DOI: doi.org/10.1007/978-3-319-62350-4
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Variable of1, of2, x1, x2;
Equation eq1, eq2, eq3, eq4;

eq1.. 4*x1 - 0.5*sqr(x2) =e= of1;
eq2.. -sqr(x1) + 5*x2    =e= of2;
eq3.. 2*x1 + 3*x2        =l= 10;
eq4.. 2*x1 -   x2        =g=  0;

x1.lo = 1; x1.up = 2;
x2.lo = 1; x2.up = 3;

Model pareto1 / all /;

Set counter / c1*c21 /;
Scalar E;
Parameter report(counter,*), ranges(*);

solve pareto1 using nlp maximizing of1;
ranges('OF1max') = of1.l;
ranges('OF2min') = of2.l;

solve pareto1 using nlp maximizing of2;
ranges('OF2max') = of2.l;
ranges('OF1min') = of1.l;

loop(counter,
   E = (ranges('OF2max') - ranges('OF2min'))*(ord(counter) - 1)/(card(counter) - 1) + ranges('OF2min');
   of2.lo = E;
   solve pareto1 using nlp maximizing of1;
   report(counter,'OF1') = of1.l;
   report(counter,'OF2') = of2.l;
   report(counter,'E')   = E;
);
display report;