```/* nag_1d_quad_wt_trig_1 (d01snc) Example Program.
*
* Copyright 2014 Numerical Algorithms Group.
*
* Mark 5, 1998.
* Mark 6 revised, 2000.
* Mark 7 revised, 2001.
*
*/

#include <nag.h>
#include <stdio.h>
#include <nag_stdlib.h>
#include <math.h>
#include <nagd01.h>
#include <nagx01.h>

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

int main(void)
{
static Integer use_comm[1] = {1};
Integer           exit_status = 0;
double            a, b;
double            omega;
double            epsabs, abserr, epsrel, result;
Nag_TrigTransform wt_func;
Integer           max_num_subint;
NagError          fail;
Nag_User          comm;

INIT_FAIL(fail);

printf("nag_1d_quad_wt_trig_1 (d01snc) Example Program Results\n");

/* For communication with user-supplied functions: */
comm.p = (Pointer)&use_comm;

epsrel = 0.0001;
epsabs = 0.0;
a = 0.0;
b = 1.0;
/* nag_pi (x01aac).
* pi
*/
omega = nag_pi * 10.0;
wt_func = Nag_Sine;
max_num_subint = 200;
* sine or cosine weight functions, thread-safe
*/
nag_1d_quad_wt_trig_1(g, a, b, omega, wt_func, epsabs, epsrel,
max_num_subint,
&result, &abserr, &qp, &comm,
&fail);
printf("a      - lower limit of integration = %10.4f\n", a);
printf("b      - upper limit of integration = %10.4f\n", b);
printf("epsabs - absolute accuracy requested = %11.2e\n", epsabs);
printf("epsrel - relative accuracy requested = %11.2e\n\n", epsrel);
if (fail.code != NE_NOERROR)
printf("Error from nag_1d_quad_wt_trig_1 (d01snc) %s\n",
fail.message);
if (fail.code != NE_INT_ARG_LT && fail.code != NE_BAD_PARAM &&
fail.code != NE_ALLOC_FAIL && fail.code != NE_NO_LICENCE)
{
printf("result - approximation to the integral = %9.5f\n",
result);
printf("abserr - estimate of the absolute error = %11.2e\n",
abserr);
printf("qp.fun_count  - number of function evaluations = %4ld\n",
qp.fun_count);
printf("qp.num_subint  - number of subintervals used = %4ld\n",
qp.num_subint);
/* Free memory used by qp */
NAG_FREE(qp.sub_int_beg_pts);
NAG_FREE(qp.sub_int_end_pts);
NAG_FREE(qp.sub_int_result);
NAG_FREE(qp.sub_int_error);
}
else
{
exit_status = 1;
goto END;
}

END:
return exit_status;
}

static double NAG_CALL g(double x, Nag_User *comm)
{
Integer *use_comm = (Integer *)comm->p;

if (use_comm[0])
{
printf("(User-supplied callback g, first invocation.)\n");
use_comm[0] = 0;
}

return (x > 0.0)?log(x):0.0;
}
```