/* nag_opt_one_var_deriv (e04bbc) Example Program.
 *
 * Copyright 1998 Numerical Algorithms Group.
 *
 * Mark 5, 1998.
 * Mark 7 revised, 2001.
 * Mark 8 revised, 2004.
 *
 */

#include <nag.h>
#include <stdio.h>
#include <nag_stdlib.h>
#include <math.h>
#include <nage04.h>

#ifdef __cplusplus
extern "C" {
#endif
  static void funct(double xc, double *fc, double *gc, Nag_Comm *comm);
#ifdef __cplusplus
}
#endif
static void funct(double xc, double *fc, double *gc, Nag_Comm *comm)
{
  *fc = sin(xc) / xc;
  *gc = (cos(xc) - *fc) / xc;
}
/* funct */

int main(void)
{
  Integer exit_status=0, max_fun;
  NagError fail;
  Nag_Comm comm;
  double a, b, e1, e2, f, g, x;

  INIT_FAIL(fail);


  Vprintf("nag_opt_one_var_deriv (e04bbc) Example Program Results.\n\n");

  /* e1 and e2 are set to zero so that nag_opt_one_var_no_deriv (e04abc) will
   *  reset them to their default values
   */
  e1 = 0.0;
  e2 = 0.0;
  /* The minimum is known to lie in the range (3.5, 5.0) */
  a = 3.5;
  b = 5.0;
  /* Allow 30 calls of funct */
  max_fun = 30;
  /* nag_opt_one_var_deriv (e04bbc).
   * Minimizes a function of one variable, requires first
   * derivatives
   */
  nag_opt_one_var_deriv(funct, e1, e2, &a, &b, max_fun, &x, &f, &g, &comm,
                        &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from nag_opt_one_var_deriv (e04bbc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }

  Vprintf("The minimum lies in the interval %7.5f to %7.5f.\n", a, b);
  Vprintf("Its estimated position is %7.5f,\n", x);
  Vprintf("where the function value is %9.4e\n",f);
  Vprintf("and the gradient is %9.4e.\n",g);
  Vprintf("%1ld function evaluations were required.\n", comm.nf);
 END:
  return exit_status;
}