/* nag_1d_spline_fit_knots (e02bac) Example Program.
 *
 * Copyright 1996 Numerical Algorithms Group.
 *
 * Mark 4, 1996.
 *
 * Mark 6 revised, 2000.
 * Mark 8 revised, 2004.
 */

#include <nag.h>
#include <stdio.h>
#include <nag_stdlib.h>
#include <nage02.h>

int main(void)
{
  Integer    exit_status = 0, j, m, ncap, ncap7, r, wght;
  NagError   fail;
  Nag_Spline spline;
  double     fit, ss, *weights = 0, *x = 0, xarg, *y = 0;

  INIT_FAIL(fail);

  /* Initialise spline */
  spline.lamda = 0;
  spline.c = 0;

  printf("nag_1d_spline_fit_knots (e02bac) Example Program Results\n");
  scanf("%*[^\n]");  /* Skip heading in data file */
  while (scanf("%ld", &m) != EOF)
    {
      if (m >= 4)
        {
          if (!(weights = NAG_ALLOC(m, double)) ||
              !(x = NAG_ALLOC(m, double)) ||
              !(y = NAG_ALLOC(m, double))
              )
            {
              printf("Allocation failure\n");
              exit_status = -1;
              goto END;
            }
        }
      else
        {
          printf("Invalid m.\n");
          exit_status = 1;
          goto END;
        }
      scanf("%ld%ld", &ncap, &wght);
      if (ncap > 0)
        {
          ncap7 = ncap+7;
          spline.n = ncap7;
          if (!(spline.lamda = NAG_ALLOC(ncap7, double)))
            {
              printf("Allocation failure\n");
              exit_status = -1;
              goto END;
            }
        }
      else
        {
          printf("Invalid ncap.\n");
          exit_status = 1;
          goto END;
        }
      for (j = 4; j < ncap+3; ++j)
        scanf("%lf", &(spline.lamda[j]));
      for (r = 0; r < m; ++r)
        {
          if (wght == 1)
            {
              scanf("%lf%lf", &x[r], &y[r]);
              weights[r] = 1.0;
            }
          else
            scanf("%lf%lf%lf", &x[r], &y[r], &weights[r]);
        }
      /* nag_1d_spline_fit_knots (e02bac).
       * Least-squares curve cubic spline fit (including
       * interpolation), one variable
       */
      nag_1d_spline_fit_knots(m, x, y, weights, &ss, &spline, &fail);
      if (fail.code != NE_NOERROR)
        {
          printf("Error from nag_1d_spline_fit_knots (e02bac).\n%s\n",
                  fail.message);
          exit_status = 1;
          goto END;
        }

      printf("\nNumber of distinct knots = %ld\n\n", ncap+1);
      printf("Distinct knots located at \n\n");
      for (j = 3; j < ncap+4; j++)
        printf("%8.4f%s", spline.lamda[j],
                (j-3)%6 == 5 || j == ncap+3?"\n":" ");
      printf("\n\n    J    B-spline coeff c\n\n");
      for (j = 0;  j < ncap+3; ++j)
        printf("    %ld  %13.4f\n", j+1, spline.c[j]);
      printf("\nResidual sum of squares = ");
      printf("%11.2e\n\n", ss);
      printf("Cubic spline approximation and residuals\n");
      printf("  r        Abscissa        Weight       Ordinate"
              "          Spline      Residual\n\n");
      for (r = 0; r < m; ++r)
        {
          /* nag_1d_spline_evaluate (e02bbc).
           * Evaluation of fitted cubic spline, function only
           */
          nag_1d_spline_evaluate(x[r], &fit, &spline, &fail);
          if (fail.code != NE_NOERROR)
            {
              printf(
                      "Error from nag_1d_spline_evaluate (e02bbc).\n%s\n",
                      fail.message);
              exit_status = 1;
              goto END;
            }

          printf("%3ld    %11.4f    %11.4f    %11.4f     %11.4f"
                  "    %10.1e\n", r+1, x[r], weights[r], y[r], fit, fit-y[r]);
          if (r < m-1)
            {
              xarg = (x[r] + x[r+1]) * 0.5;
              /* nag_1d_spline_evaluate (e02bbc), see above. */
              nag_1d_spline_evaluate(xarg, &fit, &spline, &fail);
              if (fail.code != NE_NOERROR)
                {
                  printf(
                          "Error from nag_1d_spline_evaluate (e02bbc).\n%s\n",
                          fail.message);
                  exit_status = 1;
                  goto END;
                }
              printf("    %14.4f             %33.4f\n", xarg, fit);
            }
        }
      /* Free memory used by spline */
      NAG_FREE(spline.lamda);
      NAG_FREE(spline.c);
 END:
      if (weights) NAG_FREE(weights);
      if (x) NAG_FREE(x);
      if (y) NAG_FREE(y);
    }
  return exit_status;
}