/* nag_1d_spline_interpolant(e01bac) Example Program
 *
 * Copyright 1991 Numerical Algorithms Group.
 *
 * Mark 2, 1991.
 *
 * Mark 6 revised, 2000.
 */

#include <nag.h>
#include <stdio.h>
#include <math.h>
#include <nag_stdlib.h>
#include <nage01.h>
#include <nage02.h>

#define MMAX 7
int main(void)
{
  static double x[MMAX] = {0.0, 0.2, 0.4, 0.6, 0.75, 0.9, 1.0};
  Integer i, j;
  double y[MMAX], fit, xarg;
  Nag_Spline spline;
  Integer m = MMAX;

  Vprintf("e01bac Example Program Results\n");
  for (i=0; i<m; ++i)
    y[i] = exp(x[i]);
  e01bac(m, x, y, &spline, NAGERR_DEFAULT);
  Vprintf("\nNumber of distinct knots = %ld\n\n", m-2);
  Vprintf("Distinct knots located at \n\n");
  for (j=3; j<m+1; j++)
    Vprintf("%8.4f%s",spline.lamda[j], (j-3)%5==4 || j==m ? "\n" : " ");
  Vprintf("\n\n    J    B-spline coeff c\n\n");
  for (j=0;  j<m; ++j)
    Vprintf("    %ld  %13.4f\n",j+1,spline.c[j]);
  Vprintf("\n    J       Abscissa            Ordinate            Spline\n\n");
  for (j=0; j<m; ++j)
    {
      e02bbc(x[j], &fit, &spline, NAGERR_DEFAULT);
      Vprintf("    %ld %13.4f      %13.4f       %13.4f\n",j+1,x[j],y[j],fit);
      if (j < m-1)
        {
          xarg = (x[j] + x[j+1]) * 0.5;
          e02bbc(xarg, &fit, &spline, NAGERR_DEFAULT);
          Vprintf("      %13.4f                          %13.4f\n",xarg,fit);
        }
    }
  /* Free memory allocated by e01bac */
  NAG_FREE(spline.lamda);
  NAG_FREE(spline.c);
  return EXIT_SUCCESS;
}