//      e04ya Example Program Text
//      C# version, NAG Copyright 2008
using System;
using NagLibrary;
using System.Globalization;
using System.IO;
namespace NagDotNetExamples
{
  public class E04YAE
  {
    static int mdec = 15;
    static int ndec = 3;
    static double[,] t = new double[mdec, ndec];
    static double[] y = new double[mdec];
    static string datafile = "ExampleData/e04yae.d";
    // as a command line argument. It defaults to the named file specified below otherwise.
    //
    static void Main(String[] args)
    {
      if (args.Length == 1)
      {
        datafile = args[0];
      }
      StartExample();
    }
    public static void StartExample()
    {
      E04.E04YA_LSQFUN lsqfunE04YA = new E04.E04YA_LSQFUN(lsqfun);
      try
      {
        DataReader sr = new DataReader(datafile);
        int i,  j,  m,  n;
        double[,] fjac = new double[mdec, ndec];
        double[] fvec = new double[mdec];
        double[] x = new double[ndec];
        int ifail;
        Console.WriteLine("e04ya Example Program Results");
        //      Skip heading in data file
        sr.Reset();
        n = ndec;
        m = mdec;
        //      Observations of tj (j = 1, 2, 3) are held in t[i-1, j-1]
        //      (i = 1, 2, . . . , 15)
        for (i = 1; i <= m; i++)
        {
          sr.Reset();
          y[i - 1] = double.Parse(sr.Next(), CultureInfo.InvariantCulture);
          for (j = 1; j <= n; j++)
          {
            t[i - 1, j - 1] = double.Parse(sr.Next(), CultureInfo.InvariantCulture);
          }
        }
        //      Set up an arbitrary point at which to check the 1st
        //      derivatives
        x[0] = 0.190e0;
        x[1] = -1.340e0;
        x[2] = 0.880e0;
        Console.WriteLine("");
        Console.WriteLine(" {0}", "The test point is");
        for (j = 1; j <= n; j++)
        {
          Console.Write(" " + " {0, 10:f5}", x[j - 1]);
        }
        Console.WriteLine(" ");
        //
        E04.e04ya(m, n, lsqfunE04YA, x, fvec, fjac, out ifail);
        //
        Console.WriteLine("");
        if (ifail < 0)
        {
          Console.WriteLine(" ** e04ya returned with ifail = {0, 3}", ifail);
        }
        else if (ifail == 1)
        {
          Console.WriteLine(" {0}", "A parameter is outside its expected range");
        }
        else
        {
          if (ifail == 0)
          {
            Console.WriteLine(" {0}", "1st derivatives are consistent with residual values");
          }
          else if (ifail == 2)
          {
            Console.WriteLine(" {0}\n", "Probable error in calculation of 1st derivatives");
          }
          Console.WriteLine("");
          Console.WriteLine(" {0}", "At the test point, LSQFUN gives");
          Console.WriteLine("");
          Console.WriteLine("{0}\r\n", "      Residuals                   1st derivatives");
          for (i = 1; i <= m; i++)
          {
            Console.Write(" " + "{0, 15:e3}", fvec[i - 1]);
            for (j = 1; j <= n; j++)
            {
              Console.Write(" " + "{0, 15:e3}", fjac[i - 1, j - 1]);
            }
            Console.WriteLine(" ");
          }
          Console.WriteLine(" ");
        }
        //
      }
      catch (Exception e)
      {
        Console.WriteLine(e.Message);
        Console.WriteLine( "Exception Raised");
      }
    }
    //
    public static void lsqfun(ref int iflag, int m, int n, double[] xc, double[] fvec,
    double[,] fjac)
    {
      //      Routine to evaluate the residuals and their 1st derivatives
      double denom,  dummy;
      int i = 0;
      for (i = 1; i <= m; i++)
      {
        denom = xc[1] * t[i - 1, 1] + xc[2] * t[i - 1, 2];
        if (iflag != 1)
        {
          fvec[i - 1] = xc[0] + t[i - 1, 0] / denom - y[i - 1];
        }
        if (iflag != 0)
        {
          fjac[i - 1, 0] = 1.00e0;
          dummy = -1.00e0 / (denom * denom);
          fjac[i - 1, 1] = t[i - 1, 0] * t[i - 1, 1] * dummy;
          fjac[i - 1, 2] = t[i - 1, 0] * t[i - 1, 2] * dummy;
        }
      }
    }
  }
}