```/* nag_rand_times_garch_exp (g05pgc) Example Program.
*
* Copyright 2019 Numerical Algorithms Group.
*
* Mark 27.0, 2019.
*/
/* Pre-processor includes */
#include <stdio.h>
#include <math.h>
#include <nag.h>

int main(void)
{
/* Integer scalar and array declarations */
Integer exit_status = 0;
Integer lr, i, lstate;
Integer *state = 0;

/* NAG structures */
NagError fail;
Nag_Boolean fcall;

/* Double scalar and array declarations */
double *et = 0, *ht = 0, *r = 0;

/* Number of terms to generate */
Integer num = 10;

/* Normally distributed errors */
Nag_ErrorDistn dist = Nag_NormalDistn;
Integer df = 0;

/* Set up the parameters for the series being generated */
Integer ip = 1;
Integer iq = 1;
double theta[] = { 0.1e0, -0.3e0, 0.1e0, 0.9e0 };

/* Choose the base generator */
Nag_BaseRNG genid = Nag_Basic;
Integer subid = 0;

/* Set the seed */
Integer seed[] = { 1762543 };
Integer lseed = 1;

/* Initialize the error structure */
INIT_FAIL(fail);

printf("nag_rand_times_garch_exp (g05pgc) Example Program Results\n\n\n");

/* Get the length of the state array */
lstate = -1;
nag_rand_init_repeat(genid, subid, seed, lseed, state, &lstate, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_rand_init_repeat (g05kfc).\n%s\n",
fail.message);
exit_status = 1;
goto END;
}

/* Calculate the size of the reference vector */
lr = 2 * (2 * iq + ip + 2);

/* Allocate arrays */
if (!(et = NAG_ALLOC(num, double)) ||
!(ht = NAG_ALLOC(num, double)) ||
!(r = NAG_ALLOC(lr, double)) || !(state = NAG_ALLOC(lstate, Integer)))
{
printf("Allocation failure\n");
exit_status = -1;
goto END;
}

/* Initialize the generator to a repeatable sequence */
nag_rand_init_repeat(genid, subid, seed, lseed, state, &lstate, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_rand_init_repeat (g05kfc).\n%s\n",
fail.message);
exit_status = 1;
goto END;
}

/* Generate the first realization */
fcall = Nag_TRUE;
nag_rand_times_garch_exp(dist, num, ip, iq, theta, df, ht, et, fcall, r, lr,
state, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_rand_times_garch_exp (g05pgc).\n%s\n", fail.message);
exit_status = 1;
goto END;
}

/* Display the results */
printf("  Realization Number 1\n");
printf("    I            HT(I)            ET(I)\n");
printf("   --------------------------------------\n");
for (i = 0; i < num; i++)
printf(" %5" NAG_IFMT " %16.4f %16.4f\n", i + 1, ht[i], et[i]);
printf("\n");

/*  Generate a second realization */
fcall = Nag_FALSE;
nag_rand_times_garch_exp(dist, num, ip, iq, theta, df, ht, et, fcall, r, lr,
state, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_rand_times_garch_exp (g05pgc).\n%s\n", fail.message);
exit_status = 1;
goto END;
}

/* Display the results */
printf("  Realization Number 2\n");
printf("    I            HT(I)            ET(I)\n");
printf("   --------------------------------------\n");
for (i = 0; i < num; i++)
printf(" %5" NAG_IFMT " %16.4f %16.4f\n", i + 1, ht[i], et[i]);

END:
NAG_FREE(et);
NAG_FREE(ht);
NAG_FREE(r);
NAG_FREE(state);

return exit_status;
}
```