//      c05qb Example Program Text
//      C# version, NAG Copyright 2008
using System;
using NagLibrary;
using System.Globalization;
namespace NagDotNetExamples
{
  public class C05QBE
  {
    static void Main(String[] args)
    {
      StartExample();
    }
    public static void StartExample()
    {
      try
      {
        int n = 9;
	      // C05.C05NB_FCN fcnC05NB = new C05.C05NB_FCN(fcn);
        C05.C05QB_FCN fcnC05QB = new C05.C05QB_FCN(fcn);
        double fnorm,   xtol; int i,  j; 
        double[] fvec = new double[n];
        double[] x = new double[n];
        int ifail;
        Console.WriteLine("c05qb Example Program Results");
        Console.WriteLine("");
        //      The following starting values provide a rough solution.
        for (j = 1; j <= n; j++)
        {
          x[j - 1] = -1.00e0;
        }
        xtol = Math.Sqrt(X02.x02aj());
        //
	//C05.c05nb(fcnC05NB, n, x, fvec, xtol, out ifail);
        C05.c05qb(fcnC05QB, n, x, fvec, xtol, out ifail);
        //
        if (ifail == 0)
        {
          fnorm = F06.f06ej(n, fvec, 1, out ifail);
          Console.WriteLine("  {0}{1,12:e4}", "Final 2-norm of the residuals =", fnorm);
          Console.WriteLine("");
          Console.WriteLine(" {0}", "Final approximate solution");
          Console.WriteLine("");
          for (j = 1; j <= n; j++)
          {
            Console.Write(" {0,10:f4}{1}", x[j - 1], j % 3 == 0 ? "\n" : "");
          }
          Console.WriteLine("");
        }
        else if (ifail < 0)
        {
          Console.WriteLine("");
          Console.WriteLine("** c05qb failed with ifail = {0,5}", ifail);
        }
        else
        {
          Console.WriteLine("  {0}{1,5}", "ifail = ", ifail);
          if (ifail > 1)
          {
            Console.WriteLine("");
            Console.WriteLine(" {0}", "Approximate solution");
            Console.WriteLine("");
            for (i = 1; i <= n; i++)
            {
              Console.Write(" {0}", x[i - 1]);
            }
            Console.WriteLine("");
          }
        }
        //
      }
      catch (Exception e)
      {
        Console.WriteLine(e.Message);
        Console.WriteLine("Exception Raised");
      }
      Console.WriteLine("");
    }
    //
    public static void fcn(int n, double[] x, double[] fvec, ref int iflag)
    {
      const double one = 1.00e0;
      const double two = 2.00e0;
      const double three = 3.00e0;
      for (int k = 1; k <= n; k++)
      {
        fvec[k - 1] = (three - two * x[k - 1]) * x[k - 1] + one;
        if (k > 1)
        {
          fvec[k - 1] = fvec[k - 1] - x[k - 2];
        }
        if (k < n)
        {
          fvec[k - 1] = fvec[k - 1] - two * x[k];
        }
      }
    }
  }
}