using System;

using System.Runtime.InteropServices; 

using System.Text;

using NagCFunctionsAPI;



public class NagE01Functions

{

  

    public static void nag_1d_spline_interpolant (int m, double [] x, double [] y,

                                                  ref Nag_Spline spline,

                                                  ref string error_message,

                                                  ref int fail_code)

      {   

        

        NagError fail = new NagError();

        fail.char_array = new char [512];

        //        fail.print=1;

        NagFunctions.e01bac(m, x, y, ref spline, ref fail);

        string tmpstring = new string(fail.char_array);

        error_message = tmpstring;

        fail_code = fail.code;

      } 

    public static void Main()

      {

        Nag_Spline spline= new Nag_Spline();

        int m = 7;

        double [] x = {0.0, 0.2, 0.4, 0.6, 0.75, 0.9, 1.0};

        double [] y = new double[m];

        for (int i=0; i<x.Length; i++)

          {

            y[i] = Math.Exp(x[i]);

          }

        String error_message="";

        int fail_code = 0;

        nag_1d_spline_interpolant (m, x, y, ref spline, ref error_message,

          ref fail_code);

        if (fail_code != 0)

        {

          Console.WriteLine("Error from nag_1d_spline_interpolant (e01bac).");

          Console.WriteLine(error_message);

          goto End;

        }



        double xarg;

        double fit = 0.0;

        NagError fail = new NagError();

        double [] lamda = new double[spline.n];

        double [] c = new double[spline.n];



        // Copy data from spline struct's IntPtrs to local arrays

        Marshal.Copy(spline.lamda, lamda, 0, spline.n);

        Marshal.Copy(spline.c, c, 0, spline.n);



        Console.WriteLine("\nNumber of distinct knots = {0}\n", m-2);

        Console.WriteLine("Distinct knots located at \n");

        for (int j=3; j < m+1; j++)

          if ((j-3)%5==4 || j==m)

            Console.WriteLine("{0, 8:f4}", lamda[j]);

          else

            Console.Write("{0, 8:f4} ", lamda[j]);

        Console.WriteLine("\n\n    J    B-spline coeff c\n");



        for (int j=0; j<m; ++j)

          Console.WriteLine("    {0}  {1,13:f4}", j+1, c[j]);



        Console.WriteLine("\n    J       Abscissa            Ordinate            Spline\n");

        for (int j=0; j<m; ++j)

        {

          NagFunctions.e02bbc(x[j], ref fit, ref spline, ref fail);

          if (fail.code != 0)

          {

            Console.WriteLine("Error from nag_1d_spline_evaluate (e02bbc).");

            Console.WriteLine(fail.char_array);

            goto End;

          }

          Console.WriteLine("    {0} {1,13:f4}      {2,13:f4}       {3,13:f4}", j+1, x[j], y[j], fit);

          if (j < m-1)

          {

            xarg = (x[j]+x[j+1])*0.5; // half way between these elements

            NagFunctions.e02bbc(xarg, ref fit, ref spline, ref fail);

            if (fail.code != 0)

            {

              Console.WriteLine("Error from nag_1d_spline_evaluate (e02bbc).");

              Console.WriteLine(fail.char_array);

              goto End;

            }

            Console.WriteLine("      {0,13:f4}                          {1,13:f4}", xarg, fit);

          }

        }



End:

        // Free memory allocated by nag_1d_spline_interpolant (e01bac)

        if (spline.lamda != IntPtr.Zero)

          NagFunctions.x04bdc(ref spline.lamda);

        if (spline.c != IntPtr.Zero)

          NagFunctions.x04bdc(ref spline.c);

      }

}