/******************************************************** BCL Example Problems ==================== file xbairport.java ``````````````````` QCQP problem by Rodrigo de Barros Nabholz & Maria Aparecida Diniz Ehrhardt November 1994, DMA - IMECC- UNICAMP. Based on AMPL model airport.mod by Hande Y. Benson (Source: http://www.orfe.princeton.edu/~rvdb/ampl/nlmodels/ ) (c) 2008 Fair Isaac Corporation author: S.Heipcke, June 2008, rev. Dec. 2011 ********************************************************/ import java.io.*; import com.dashoptimization.*; public class xbairport { static final int N = 42; static final double CX[] = {-6.3, -7.8, -9, -7.2, -5.7, -1.9, -3.5, -0.5, 1.4, 4, 2.1, 5.5, 5.7, 5.7, 3.8, 5.3, 4.7, 3.3, 0, -1, -0.4, 4.2, 3.2, 1.7, 3.3, 2, 0.7, 0.1, -0.1, -3.5, -4, -2.7, -0.5, -2.9, -1.2, -0.4, -0.1, -1, -1.7, -2.1, -1.8, 0}; static final double CY[] = {8, 5.1, 2, 2.6, 5.5, 7.1, 5.9, 6.6, 6.1, 5.6, 4.9, 4.7, 4.3, 3.6, 4.1, 3, 2.4, 3, 4.7, 3.4, 2.3, 1.5, 0.5, -1.7, -2, -3.1, -3.5, -2.4, -1.3, 0, -1.7, -2.1, -0.4, -2.9, -3.4, -4.3, -5.2, -6.5, -7.5, -6.4, -5.1, 0}; static final double R[] = {0.09, 0.3, 0.09, 0.45, 0.5, 0.04, 0.1, 0.02, 0.02, 0.07, 0.4, 0.045, 0.05, 0.056, 0.36, 0.08, 0.07, 0.36, 0.67, 0.38, 0.37, 0.05, 0.4, 0.66, 0.05, 0.07, 0.08, 0.3, 0.31, 0.49, 0.09, 0.46, 0.12, 0.07, 0.07, 0.09, 0.05, 0.13, 0.16, 0.46, 0.25, 0,1}; public static void main(String[] args) throws IOException { int i,j; XPRBvar[] x,y; /* x-/y-coordinates to determine */ XPRBexpr qe; XPRBctr cobj, c; try (XPRBprob prob = new XPRBprob("airport")) { /* Initialize BCL and create a new problem */ /**** VARIABLES ****/ x = new XPRBvar[N]; for(i=0;i<N;i++)
                x[i] = prob.newVar("x(" + (i+1) + ")", XPRB.PL, -10, 10);
            y = new XPRBvar[N];
            for(i=0;i<N;i++)
                y[i] = prob.newVar("y(" + (i+1) + ")", XPRB.PL, -10, 10);

            /****OBJECTIVE****/
            /* Minimize the total distance between all points */
            /*  sum(i in 1..N-1,j in i+1..N) ((x(i)-x(j))^2+(y(i)-y(j))^2)  */
            qe = new XPRBexpr();
            for(i=0;i<N-1;i++)
                for(j=i+1;j<N;j++) qe .add((x[i].add(x[j].mul(-1))).sqr())
                                       .add((y[i].add(y[j].mul(-1))).sqr());
            cobj = prob.newCtr("TotDist", qe);
            prob.setObj(cobj);                     /* Set objective function */

            /**** CONSTRAINTS ****/
            /* All points within given distance of their target location */
            /*  (x(i)-CX(i))^2+(y(i)-CY(i))^2 <= R(i)  */
            for(i=0;i<N;i++)
                c = prob.newCtr("LimDist", (x[i].add(-CX[i])).sqr()
                                .add( (y[i].add(-CY[i])).sqr()) .lEql(R[i]) );

            /****SOLVING + OUTPUT****/
            prob.setSense(XPRB.MINIM);             /* Choose the sense of optimization */

            /* Problem printing and matrix output: */
            /*
              prob.print();
              prob.exportProb(XPRB.MPS, "airport");
              prob.exportProb(XPRB.LP, "airport");
            */

            prob.lpOptimize("");                   /* Solve the problem */

            System.out.println("Solution: " + prob.getObjVal());
            for(i=0;i<N;i++)
                System.out.println(x[i].getName() + ": " + x[i].getSol() + ", " +
                                   y[i].getName() + ": " + y[i].getSol());
        }
    }
}