NAG Library Manual, Mark 29.3
```/* nag_inteq_volterra_weights (d05bwc) Example Program.
*
* Copyright 2023 Numerical Algorithms Group.
*
* Mark 29.3, 2023.
*/
#include <nag.h>

int main(void) {
/* Scalars */
Integer exit_status = 0;
Integer i, iorder, j, nomg, p, n;
char methodstring[10];
/* Arrays */
double *omega = 0, *sw = 0;
/* NAG types */
NagError fail;
Nag_ODEMethod method;

INIT_FAIL(fail);

printf("nag_inteq_volterra_weights (d05bwc) Example Program Results\n");

/* Skip heading in data file */
scanf("%*[^\n] ");
scanf("%9s%*[^\n] ", methodstring);

/*
* nag_enum_name_to_value (x04nac).
* Converts NAG enum member name to value.
*/
method = (Nag_ODEMethod)nag_enum_name_to_value(methodstring);
scanf("%" NAG_IFMT "%*[^\n] ", &iorder);
scanf("%" NAG_IFMT "%*[^\n] ", &nomg);

switch (method) {
p = iorder - 1;
break;
case Nag_BDF:
p = iorder;
break;
}

n = nomg + p - 1;

if (!(omega = NAG_ALLOC(nomg, double)) || !(sw = NAG_ALLOC(p * n, double))) {
printf("Allocation failure\n");
exit_status = -1;
goto END;
}

/*
nag_inteq_volterra_weights (d05bwc).
Generate weights for use in solving Volterra equations.
*/
nag_inteq_volterra_weights(method, iorder, nomg, omega, sw, &fail);

if (fail.code != NE_NOERROR) {
printf("Error from nag_inteq_volterra_weights (d05bwc).\n%s\n",
fail.message);
exit_status = 1;
goto END;
}

printf("\nThe convolution weights\n\n  n-j        omega\n");
for (j = 0; j < nomg; j++)
printf("%3" NAG_IFMT "     %10.4f\n", j + 1, omega[j]);

printf("\nThe weights W\n");
printf("\n  i ");
for (j = 0; j < p; j++)
printf("%11s%" NAG_IFMT " ", "j = ", j);
printf("\n");

#define SW(I, J) sw[J * n + I]

for (i = 0; i < n; i++) {
printf("%3" NAG_IFMT "", i + 1);
for (j = 0; j < p; j++)
printf("%13.4f", SW(i, j));
printf("\n");
}

#undef SW

END:

NAG_FREE(sw);
NAG_FREE(omega);

return exit_status;
}
```