NAG Library Manual, Mark 27.2
```/* nag_specfun_bessel_i1_scaled_vector (s18ctc) Example Program.
*
* Copyright 2021 Numerical Algorithms Group.
*
* Mark 27.2, 2021.
*/
#include <nag.h>
#include <stdio.h>

int main(void) {
Integer exit_status = 0;
Integer i, n;
double *f = 0, *x = 0;
NagError fail;

INIT_FAIL(fail);

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

printf(
"nag_specfun_bessel_i1_scaled_vector (s18ctc) Example Program Results\n");
printf("\n");
printf("     x           f\n");
printf("\n");
scanf("%" NAG_IFMT "", &n);
scanf("%*[^\n]");

/* Allocate memory */
if (!(x = NAG_ALLOC(n, double)) || !(f = NAG_ALLOC(n, double))) {
printf("Allocation failure\n");
exit_status = -1;
goto END;
}

for (i = 0; i < n; i++)
scanf("%lf", &x[i]);
scanf("%*[^\n]");

/* nag_specfun_bessel_i1_scaled_vector (s18ctc).
* scaled modified Bessel Function exp(-|x|) I1(x)
*/
nag_specfun_bessel_i1_scaled_vector(n, x, f, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_specfun_bessel_i1_scaled_vector (s18ctc).\n%s\n",
fail.message);
exit_status = 1;
goto END;
}

for (i = 0; i < n; i++)
printf(" %11.3e %11.3e\n", x[i], f[i]);

END:
NAG_FREE(f);
NAG_FREE(x);

return exit_status;
}
```