using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;
using NagCFunctionsAPI;

namespace E02ADC
{
    class Program
    {
        static void Main(string[] args)
        {
            double[] x = { 0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0, 13.0 };
            double[] y = { 0, 0.841470985, 0.909297427, 0.141120008, -0.756802495, -0.958924275, -0.279415498, 0.656986599, 0.989358247, 0.412118485, -0.544021111, -0.999990207, -0.536572918, 0.420167037 };
            double[] w = { 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0 };

            Console.WriteLine("Please pass a value for the degree k of the polynomial (less than 14, i.e., the number of points): ");
            int k = Convert.ToInt32(Console.ReadLine());
            int kplus1 = k + 1;
            int lda = kplus1;
            double[,] a = new double[kplus1, kplus1];
            double[] s = new double[kplus1];
            double[] ak = new double[kplus1];
            double xcap, xarg;
            double fit = 0.0D;
            int m = x.Length;

            NagError fail = new NagError();

            try
            {
                NagFunctions.e02adc(m, kplus1, lda, x, y, w, a, s, ref fail);
                switch (fail.code)
                {
                    case 249:
                        throw new Exception("The weights are not all strictly positive.");
                    case 66:
                        throw new Exception("The values of x[r], for r = 0, 1, 2, . . . ,m-1, are not in nondecreasing order.");
                    case 67:
                        throw new Exception("All x[r] have the same value: thus the normalization of x is not possible.");
                    case 11:
                        throw new Exception("On entry, kplus1 < 1 (so the maximum degree required is negative) or kplus1 > mdist, where mdist is the number of distinct x values in the data (so there cannot be a unique solution for degree k = kplus1 - 1).");
                    case 17:
                        throw new Exception("lda < kplus1.");
                    default:
                        break;
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }

            for (int j = 0; j <= k; j++)
            {
                ak[j] = a[k, j];
            }

            if (fail.code == 0)
            {
                Console.WriteLine("\nAbscissa    Polynomial\n");
                //evaluate at different points
                for (int i = 0; i <= m - 1; i++)
                {
                    xcap = ((x[i] - x[0]) - (x[m - 1] - x[i])) / (x[m - 1] - x[0]);

                    try
                    {
                        NagFunctions.e02aec(kplus1, ak, xcap, ref fit, ref fail);
                        switch (fail.code)
                        {
                            case 280:
                                throw new Exception("ABS(xcap)> 1.0 + 4*eps, where eps is the machine precision. In this case the value of p is set arbitrarily to zero");
                            case 11:
                                throw new Exception("On entry, nplus1 < 1.");
                            default:
                                break;
                        }
                    }
                    catch (Exception ex)
                    {
                        Console.WriteLine(ex.Message);
                        break;
                    }

                    Console.WriteLine("{0} \t {1, 10:f4}", x[i], fit);

                    if (i < m - 1)
                    {
                        xarg = 0.5 * (x[i] + x[i + 1]);
                        xcap = ((xarg - x[0]) - (x[m - 1] - xarg)) / (x[m - 1] - x[0]);

                        try
                        {
                            NagFunctions.e02aec(kplus1, ak, xcap, ref fit, ref fail);
                            switch (fail.code)
                            {
                                case 280:
                                    throw new Exception("ABS(xcap)> 1.0 + 4*eps, where eps is the machine precision. In this case the value of p is set arbitrarily to zero.");
                                case 11:
                                    throw new Exception("On entry, nplus1 < 1.");
                                default:
                                    break;
                            }
                        }
                        catch (Exception ex)
                        {
                            Console.WriteLine(ex.Message);
                            break;
                        }

                        Console.WriteLine("{0} \t {1, 10:f4}", xarg, fit);
                    }
                }
            }

        }
    }
}