/* nag_zero_cont_func_bd (c05adc) Example Program.
 *
 * Copyright 1991 Numerical Algorithms Group.
 *
 * Mark 2, 1991.
 * Mark 7 revised, 2001.
 */

#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);
#ifdef __cplusplus
}
#endif

int main(int argc, char *argv[])
{
  FILE     *fpout;
  Integer  exit_status = 0;
  double   a, b;
  double   x, ftol, xtol;
  NagError fail;

  INIT_FAIL(fail);

  /* Check for command-line IO options */
  fpout = nag_example_file_io(argc, argv, "-results", NULL);
  fprintf(fpout, "nag_zero_cont_func_bd (c05adc) Example Program Results\n");
  a = 0.0;
  b = 1.0;
  xtol = 1e-05;
  ftol = 0.0;
  /* nag_zero_cont_func_bd (c05adc).
   * Zero of a continuous function of one variable
   */
  nag_zero_cont_func_bd(a, b, &x, f, xtol, ftol, &fail);
  if (fail.code == NE_NOERROR)
    {
      fprintf(fpout, "Zero = %12.5f\n", x);
    }
  else
    {
      fprintf(fpout, "%s\n", fail.message);
      if (fail.code == NE_XTOL_TOO_SMALL ||
          fail.code == NE_PROBABLE_POLE)
        fprintf(fpout, "Final point = %12.5f\n", x);
      exit_status = 1;
      goto END;
    }

 END:
  if (fpout != stdout) fclose(fpout);
  return exit_status;
}

static double NAG_CALL f(double x)
{
  return exp(-x)-x;
}