/* nag_rand_init_nonrepeat (g05kgc) Example Program.
*
* Copyright 2023 Numerical Algorithms Group.
*
* Mark 29.2, 2023.
*/
/* Pre-processor includes */
#include <math.h>
#include <nag.h>
#include <stdio.h>
int main(void) {
/* Integer scalar and array declarations */
Integer exit_status = 0;
Integer i, lstate, same;
Integer *state = 0, *x1 = 0, *x2 = 0;
/* NAG structures */
NagError fail;
/* Set the sample size */
Integer n = 500;
/* Choose the base generator */
Nag_BaseRNG genid = Nag_MersenneTwister;
Integer subid = 0;
/* Initialize the error structure */
INIT_FAIL(fail);
printf("nag_rand_init_nonrepeat (g05kgc) Example Program Results\n\n");
/* Get the length of the state array */
lstate = -1;
nag_rand_init_nonrepeat(genid, subid, state, &lstate, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_rand_init_nonrepeat (g05kgc).\n%s\n", fail.message);
exit_status = 1;
goto END;
}
/* Allocate arrays */
if (!(x1 = NAG_ALLOC(n, Integer)) || !(x2 = NAG_ALLOC(n, Integer)) ||
!(state = NAG_ALLOC(lstate, Integer))) {
printf("Allocation failure\n");
exit_status = -1;
goto END;
}
/* Initialize the generator to a non-repeatable sequence */
nag_rand_init_nonrepeat(genid, subid, state, &lstate, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_rand_init_nonrepeat (g05kgc).\n%s\n", fail.message);
exit_status = 1;
goto END;
}
/* Generate a sample of values from a discrete uniform distribution */
nag_rand_int_uniform(n, -100, 100, state, x1, &fail);
/* Re-initialize the generator to another non-repeatable sequence
NB: In practice, in order to preserve its statistical properties,
you should only initialize the RNG generators once */
nag_rand_init_nonrepeat(genid, subid, state, &lstate, &fail);
/* Generate a second sample of values from the same distribution */
nag_rand_int_uniform(n, -100, 100, state, x2, &fail);
/* Check that the two samples are different */
same = 1;
for (i = 0; i < n; i++) {
if (x1[i] != x2[i]) {
same = 0;
break;
}
}
if (same) {
printf("The two samples are the same\n");
printf("whilst this is possible, it is unlikely\n");
} else {
printf("The two samples differ, as expected\n");
}
END:
NAG_FREE(x1);
NAG_FREE(x2);
NAG_FREE(state);
return exit_status;
}