```/* nag_zero_cont_func_brent_binsrch (c05auc) Example Program.
*
* Copyright 2017 Numerical Algorithms Group.
*
* Mark 26.2, 2017.
*/

#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;
/* Arrays */
static double ruser[1] = { -1.0 };

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;

/* For communication with user-supplied functions: */
comm.user = ruser;

/* 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)
{
if (comm->user[0] == -1.0) {
printf("(User-supplied callback f, first invocation.)\n");
comm->user[0] = 0.0;
}
return x - exp(-x);
}
```