NAG Library Manual, Mark 27.2
```/* nag_quad_dim1_gauss_recm (d01tec) Example Program.
*
* Copyright 2021 Numerical Algorithms Group.
*
* Mark 27.2, 2021.
*/

#include <math.h>
#include <nag.h>
#include <stdio.h>

int main(void) {
/* Scalars */
Integer exit_status = 0;
Integer n, i;
double ri, muzero;
/* Arrays */
double *a = 0, *b = 0, *c = 0, *abscissae = 0, *weights = 0, *mu = 0;
/* Nag Types */
NagError fail;

INIT_FAIL(fail);

/* Skip heading in data file */
scanf("%*[^\n] ");
/* Input number of abscissae required, n */
scanf("%" NAG_IFMT "%*[^\n] ", &n);

/* Allocate coefficient, weight and abscissae arrays */
if (!(a = NAG_ALLOC(n, double)) || !(b = NAG_ALLOC(n, double)) ||
!(c = NAG_ALLOC(n, double)) || !(mu = NAG_ALLOC(2 * n + 1, double)) ||
!(abscissae = NAG_ALLOC(n, double)) ||
!(weights = NAG_ALLOC(n, double))) {
printf("Allocation failure\n");
exit_status = -1;
goto END;
}

/* Set up moments w.r.t w(x)x^j in array mu */
mu[0] = 2.0;
for (i = 1; i < 2 * n; i = i + 2) {
ri = (double)(i + 2);
mu[i] = 0.0;
mu[i + 1] = 2.0 / ri;
}

* Compute three term recurrence coefficients from moments in w(x)x^j.
*/
nag_quad_dim1_gauss_recm(n, mu, a, b, c, &fail);
if (fail.code != NE_NOERROR) {
exit_status = 1;
goto END;
}

printf("\n       a         b         c\n");
for (i = 0; i < n; i++) {
printf("%10.5f%10.5f%10.5f\n", a[i], b[i], c[i]);
}

* Compute weights and abscissae for a Gaussian quadrature rule
* governed by a three-term recurrence relation.
*/
muzero = mu[0];
nag_quad_dim1_gauss_wrec(n, a, b, c, muzero, weights, abscissae, &fail);
if (fail.code != NE_NOERROR) {
exit_status = 2;
goto END;
}

printf("\n   weights       abscissae\n");
for (i = 0; i < n; i++) {
printf("%10.5f     %10.5f\n", weights[i], abscissae[i]);
}

END:
NAG_FREE(a);
NAG_FREE(b);
NAG_FREE(c);
NAG_FREE(mu);
NAG_FREE(abscissae);
NAG_FREE(weights);

return exit_status;
}
```