/**
 * Description: Benchmark function (Pressure Vessel).
 * X*(Optimal point):
 * X1=42.09844546451396
 * X2=176.63659783549562
 * X3=13  (Discrete variable)
 * X4=7   (Discrete variable)
 * Y*(Optimal value)
 * Y1=6059.714359589802
 *
 * @ Author        Create/Modi     Note
 * Xiaofeng Xie    Mar 02, 2003
 * Xiaofeng Xie    May 11, 2004
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * Please acknowledge the author(s) if you use this code in any way.
 *
 * @version 1.0
 * @Since MAOS1.0
 *
 * @References:
 * [1]	Coello C A C. Theoretical and numerical constraint-handling techniques
 * used with evolutionary algorithms: a survey of the state of the art. Computer
 * Methods in Applied Mechanics and Engineering, 2002, 191(11-12): 1245-1287
 */

package problem.constrained;

import problem.*;
import Global.*;

public class PressureVessel extends ProblemEncoder {
  static final int NX = 4;
  static final int NY = 5;
  public PressureVessel() throws Exception {
    super(NX, NY);

    for(int i=0; i<2; i++) {
      setDefaultXAt(i, 10, 200);
    }
    for(int i=2; i<NX; i++) {
      setDefaultXAt(i, 1, 99, 1);  //[1, 99] The integer variables: set grain=1
    }

    setDefaultYAt(0, BasicBound.MINDOUBLE, BasicBound.MINDOUBLE); // Minimize Objective
    for(int i=1; i<NY; i++) {
      setDefaultYAt(i, BasicBound.MINDOUBLE, 0);
    }
  }

  protected double calcTargetAt(int index, double[] VX) {
    double value = 0;
    switch(index) {
      case 0:
        value = value =0.6224*0.0625*VX[2]*VX[1]*VX[0]+1.7781*0.0625*VX[3]*VX[0]*VX[0]+(0.0625*VX[2])*(0.0625*VX[2])*(3.1661*VX[1])+19.84*(0.0625*VX[2])*(0.0625*VX[2])*VX[0];
        break;
      case 1:
        value = 0.0193*VX[0]-0.0625*VX[2];
        break;
      case 2:
        value = 0.00954*VX[0]-0.0625*VX[3];
        break;
      case 3:
        value = 750.0*1728.0-Math.PI*VX[0]*VX[0]*VX[1]-Math.PI*VX[0]*VX[0]*VX[0]*4.0/3.0;
        break;
      case 4:
        value = VX[1]-240;
        break;
      default:
        return Double.NaN;
    }
    return value;
  }
}