/* nag_monotonic_deriv (e01bgc) Example Program.
 *
 * Copyright 1991 Numerical Algorithms Group.
 *
 * Mark 2, 1991.
 * Mark 8 revised, 2004.
 */

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

int main(void)
{
  Integer exit_status=0, i, m, n, r;
  NagError fail;
  double *d=0, *f=0, *pd=0, *pf=0, *px=0, step, *x=0;

  INIT_FAIL(fail);
  Vprintf("nag_monotonic_deriv (e01bgc) Example Program Results\n");
  Vscanf("%*[^\n]");  /* Skip heading in data file */
  Vscanf("%ld",&n);
  if (n>=2)
    {
      if ( !( x = NAG_ALLOC(n, double)) ||
           !( f = NAG_ALLOC(n, double)) ||
           !( d = NAG_ALLOC(n, double))  )
        {
          Vprintf("Allocation failure\n");
          exit_status = -1;
          goto END;

        }
    }
  else
    {
      Vprintf("Invalid n.\n");
      exit_status = 1;
      return exit_status;
    }
  for (r=0; r<n; r++)
    Vscanf("%lf%lf%lf",&x[r], &f[r], &d[r]);
  Vscanf("%ld",&m);
  if (m>=1)
    {
      if ( !( pd = NAG_ALLOC(m, double)) ||
           !( pf = NAG_ALLOC(m, double)) ||
           !( px = NAG_ALLOC(m, double)) )
        {
          Vprintf("Allocation failure\n");
          exit_status = -1;
          goto END;

        }
    }
  else
    {
      Vprintf("Invalid m.\n");
      exit_status = 1;
      return exit_status;
    }
  /* compute m equally spaced points from x[0] to x[n-1]. */
  step = (x[n-1]-x[0]) / (double)(m-1);
  for (i=0; i<m; i++)
    px[i] = MIN(x[0]+i*step,x[n-1]);
  /* nag_monotonic_deriv (e01bgc).
   * Evaluation of interpolant computed by
   * nag_monotonic_interpolant (e01bec), function and first
   * derivative
   */
  nag_monotonic_deriv(n, x, f, d, m, px, pf, pd, &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from nag_monotonic_deriv (e01bgc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  Vprintf("                            Interpolated");
  Vprintf("      Interpolated\n");
  Vprintf("       Abscissa                Value");
  Vprintf("           Derivative\n");
  for (i=0; i<m; i++)
    Vprintf("%15.4f      %15.4f      %15.3e\n",px[i],pf[i],pd[i]);
 END:
  if (x) NAG_FREE(x);
  if (pd) NAG_FREE(pd);
  if (pf) NAG_FREE(pf);
  if (px) NAG_FREE(px);
  if (f) NAG_FREE(f);
  if (d) NAG_FREE(d);
  return exit_status;
}