```/* nag_1d_quad_wt_alglog_1 (d01spc) Example Program.
*
* NAGPRODCODE Version.
*
* Copyright 2016 Numerical Algorithms Group.
*
* Mark 26, 2016.
*
*/

#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 f_sin(double x, Nag_User *comm);
static double NAG_CALL f_cos(double x, Nag_User *comm);
#ifdef __cplusplus
}
#endif

int main(void)
{
/* Scalars */
Integer exit_status = 0;
Integer max_num_subint, wt_array_ind;
int numfunc;
double a, b, epsabs, abserr, epsrel, result;
/* Arrays */
static Integer use_comm[2] = { 1, 1 };
static double alpha[2] = { 0.0, -0.5 };
static double beta[2] = { 0.0, -0.5 };
static const char *Nag_QuadWeight_array[] = { "Nag_Alg", "Nag_Alg_loga",
"Nag_Alg_logb", "Nag_Alg_loga_logb"
};
/* Nag Types */
Nag_User comm;
NagError fail;

INIT_FAIL(fail);

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

epsabs = 0.0;
epsrel = 0.0001;
a = 0.0;
b = 1.0;
max_num_subint = 200;
for (numfunc = 0; numfunc < 2; ++numfunc) {
switch (numfunc) {
default:
case 0:
wt_func = Nag_Alg_loga;
wt_array_ind = 1;
* end-point singularities of algebraic-logarithmic type,
*/
wt_func, epsabs, epsrel, max_num_subint,
&result, &abserr, &qp, &comm, &fail);
printf("\nIntegral of cos(10*pi*x) on [a,b]\n");
break;
case 1:
wt_func = Nag_Alg;
wt_array_ind = 0;
wt_func, epsabs, epsrel, max_num_subint,
&result, &abserr, &qp, &comm, &fail);
printf("\nIntegral of sin(10*x) on [a,b]\n");
}
printf("---------------------------------\n");
printf("a       - lower limit of integration    = %9.4f\n", a);
printf("b       - upper limit of integration    = %9.4f\n", b);
printf("epsabs  - absolute accuracy requested   = %11.2e\n", epsabs);
printf("epsrel  - relative accuracy requested   = %11.2e\n\n", epsrel);
printf("alpha   - weight function parameter     = %9.4f\n",
alpha[numfunc]);
printf("beta    - weight function parameter     = %9.4f\n",
beta[numfunc]);
printf("wt_func - weight function used          =  %s\n",

if (fail.code != NE_NOERROR)
printf("%s\n", fail.message);

{
printf("result  - approximation to the integral = %10.5f\n", result);
printf("abserr  - estimate of absolute error    = %11.2e\n", abserr);
printf("qp.fun_count  - function evaluations    = %4" NAG_IFMT "\n",
qp.fun_count);
printf("qp.num_subint - subintervals used       = %4" NAG_IFMT "\n\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 f_cos(double x, Nag_User *comm)
{
double a;
double pi;
Integer *use_comm = (Integer *) comm->p;

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

/* nag_pi (x01aac). */
pi = nag_pi;
a = pi * 10.0;
return cos(a * x);
}

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

if (use_comm[1]) {
printf("(User-supplied callback f_sin, first invocation.)\n");
use_comm[1] = 0;
}

omega = 10.0;
return sin(omega * x);
}
```