/* nag_zero_cont_func_brent_binsrch (c05auc) Example Program.
 *
 * Copyright 2011 Numerical Algorithms Group.
 *
 * Mark 23, 2011.
 */

#include <nag.h>
#include <nagx04.h>
#include <stdio.h>
#include <nag_stdlib.h>
#include <math.h>
#include <nagc05.h>

#ifdef __cplusplus
extern "C" {
#endif
static double NAG_CALL f(double x, Nag_Comm *comm);
#ifdef __cplusplus
}
#endif

int main(void)
{
  /* Scalars */
  Integer  exit_status = 0;
  double   a, b, eps, eta, h, x;
  NagError fail;
  Nag_Comm comm;

  INIT_FAIL(fail);

  printf("nag_zero_cont_func_brent_binsrch (c05auc) Example Program Results\n");

  x = 1.0;
  h = 0.1;
  eps = 1e-05;
  eta = 0.0;
  /* nag_zero_cont_func_brent_binsrch (c05auc).
   * Locates a simple zero of a continuous function of one variable,
   * binary search for an interval containing a zero.
   */
  nag_zero_cont_func_brent_binsrch(&x, h, eps, eta, f, &a, &b, &comm, &fail);
  if (fail.code == NE_NOERROR)
    {
      printf("Root is %13.5f\n", x);
      printf("Interval searched is [%8.5f,%8.5f]\n", a, b);
    }
  else
    {
      printf("%s\n", fail.message);
      if (fail.code == NE_PROBABLE_POLE ||
          fail.code == NW_TOO_MUCH_ACC_REQUESTED)
        printf("Final value = %13.5f\n", x);
      exit_status = 1;
      goto END;
    }

 END:
  return exit_status;
}

static double NAG_CALL f(double x, Nag_Comm *comm)
{
  return x - exp(-x);
}