/* nag_zero_cont_func_cntin (c05awc) 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>
#include <nagx02.h>

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

int main(void)
{
  /* Scalars */
  Integer          nfmax, exit_status = 0;
  double           eps, eta, x, i;

  NagError         fail;
  Nag_Comm         comm;

  printf(
          "nag_zero_cont_func_cntin (c05awc) Example Program Results\n");

  for (i = 3; i <= 4; i++)
    {
      eps = pow(10.0, -i);
      x = 1.0;
      eta = 0.0;
      nfmax = 200;

      INIT_FAIL(fail);

      /* nag_zero_cont_func_cntin (c05awc).
       * Locates a zero of a continuous function.
       */
      nag_zero_cont_func_cntin(&x, eps, eta, f, nfmax, &comm, &fail);

      if (fail.code == NE_NOERROR)
        {
          printf("\nWith eps = %10.2e, root is %14.5f\n", eps, x);
        }
      else
        {
          printf(
                  "Error from nag_zero_cont_func_cntin (c05awc) %s\n",
                  fail.message);

          if (fail.code == NE_TOO_MANY_CALLS ||
              fail.code == NE_SECANT_ITER_FAILED)
            {
              printf("\nWith eps = %10.2e, final value is %14.5f\n",
                      eps, x);
            }

          exit_status = 1;
          goto END;
        }
    }

 END:

  return exit_status;
}

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