//      e04hd Example Program Text
//      C# version, NAG Copyright 2008
using System;
using NagLibrary;
using System.Globalization;
using System.IO;
namespace NagDotNetExamples
{
  public class E04HDE
  {
    static void Main(String[] args)
    {
      StartExample();
    }
    public static void StartExample()
    {
      E04.E04HC_FUNCT functE04HC = new E04.E04HC_FUNCT(funct);
      E04.E04HD_FUNCT functE04HD = new E04.E04HD_FUNCT(funct);
      E04.E04HD_H hE04HD = new E04.E04HD_H(h);
      try
      {
        double f = 0.0;
        int i,  ifail,  j,  k;
        int n = 4;
        int lh = n * (n - 1) / 2;
        int lw = 5 * n;
        double[] g = new double[n];
        double[] hesd = new double[n];
        double[] hesl = new double[lh];
        double[] w = new double[lw];
        double[] x = new double[n];
        int[] iw = new int[1];
        Console.WriteLine("e04hd Example Program Results");
        //      Set up an arbitrary point at which to check the derivatives
        x[0] = 1.460e0;
        x[1] = -0.820e0;
        x[2] = 0.570e0;
        x[3] = 1.210e0;
        Console.WriteLine("");
        Console.WriteLine(" {0}", "The test point is");
        for (j = 1; j <= n; j++)
        {
          Console.Write(" " + " {0, 9:f4}", x[j - 1]);
        }
        Console.WriteLine(" ");
        //      Check the 1st derivatives
        //
        E04.e04hc(n, functE04HC, x, out f, g, out ifail);
        if (ifail != 0)
        {
          Console.WriteLine("");
          Console.WriteLine(" ** e04hc returned with ifail = {0, 3}", ifail);
          goto L40;
        }
        //
        //      Check the 2nd derivatives
        E04.e04hd(n, functE04HD, hE04HD, x, g, hesl, hesd, out ifail);
        //
        Console.WriteLine("");
        if (ifail == 1)
        {
          Console.WriteLine(" {0}", "A parameter is outside its expected range");
        }
        else if (ifail >= 0)
        {
          if (ifail == 0)
          {
            Console.WriteLine(" {0}", "2nd derivatives are consistent with 1st derivatives");
          }
          else if (ifail == 2)
          {
            Console.WriteLine(" {0}", "Probable error in calculation of 2nd derivatives");
          }
          Console.WriteLine("");
          Console.WriteLine("  {0}{1,12:e4}", "At the test point, FUNCT gives the function value", f);
          Console.WriteLine(" {0}", "and the 1st derivatives");
          for (j = 1; j <= n; j++)
          {
            Console.Write(" " + " {0, 12:e3}", g[j - 1]);
          }
          Console.WriteLine(" ");
          Console.WriteLine("");
          Console.WriteLine(" {0}", "H gives the lower triangle of the Hessian matrix");
          Console.WriteLine("  {0,12:e3}", hesd[0]);
          k = 1;
          for (i = 2; i <= n; i++)
          {
            for (j = k; j <= k + i - 2; j++)
            {
              Console.Write(" " + " {0, 12:e3}", hesl[j - 1]);
            }
            Console.Write(" " + " {0, 12:e3}", hesd[i - 1]);
            Console.WriteLine(" ");
            k = k + i - 1;
          }
        }
        else
        {
          if (ifail < 0)
          {
            Console.WriteLine("  IFLAG was set to {0,5}in FUNCT or H", ifail);
          }
        }
        //
        L40: ;
        //
      }
      catch (Exception e)
      {
        Console.WriteLine(e.Message);
        Console.WriteLine( "Exception Raised");
      }
    }
    //
    public static void funct(ref int iflag, int n, double[] xc, ref double fc,
    double[] gc)
    {
      //      Routine to evaluate objective function and its 1st derivatives.
      fc = ((xc[0] + 10.00e0 * xc[1])) * ((xc[0] + 10.00e0 * xc[1])) + 5.00e0 * ((xc[2] - xc[3])) * ((xc[2] - xc[3])) + Math.Pow((xc[1] - 2.00e0 * xc[2]), 4) + 10.00e0 * Math.Pow((xc[0] - xc[3]), 4);
      gc[0] = 2.00e0 * (xc[0] + 10.00e0 * xc[1]) + 40.00e0 * Math.Pow((xc[0] - xc[3]), 3);
      gc[1] = 20.00e0 * (xc[0] + 10.00e0 * xc[1]) + 4.00e0 * Math.Pow((xc[1] - 2.00e0 * xc[2]), 3);
      gc[2] = 10.00e0 * (xc[2] - xc[3]) - 8.00e0 * Math.Pow((xc[1] - 2.00e0 * xc[2]), 3);
      gc[3] = 10.00e0 * (xc[3] - xc[2]) - 40.00e0 * Math.Pow((xc[0] - xc[3]), 3);
    }
    //
    public static void h(ref int iflag, int n, double[] xc, double[] fhesl,
    double[] fhesd)
    {
      //      Routine to evaluate 2nd derivatives
      fhesd[0] = 2.00e0 + 120.00e0 * ((xc[0] - xc[3])) * ((xc[0] - xc[3]));
      fhesd[1] = 200.00e0 + 12.00e0 * ((xc[1] - 2.00e0 * xc[2])) * ((xc[1] - 2.00e0 * xc[2]));
      fhesd[2] = 10.00e0 + 48.00e0 * ((xc[1] - 2.00e0 * xc[2])) * ((xc[1] - 2.00e0 * xc[2]));
      fhesd[3] = 10.00e0 + 120.00e0 * ((xc[0] - xc[3])) * ((xc[0] - xc[3]));
      fhesl[0] = 20.00e0;
      fhesl[1] = 0.00e0;
      fhesl[2] = -24.00e0 * ((xc[1] - 2.00e0 * xc[2])) * ((xc[1] - 2.00e0 * xc[2]));
      fhesl[3] = -120.00e0 * ((xc[0] - xc[3])) * ((xc[0] - xc[3]));
      fhesl[4] = 0.00e0;
      fhesl[5] = -10.00e0;
    }
  }
}