/* nag_rand_init_skipahead_power2 (g05kkc) Example Program.
 *
 * Copyright 2021 Numerical Algorithms Group.
 *
 * Mark 27.2, 2021.
 */

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

#define LSEED 1

int main(void) {
  /* Scalars */
  Integer exit_status = 0;
  Integer lstate, n, nv, subid, i;
  /* Arrays */
  Integer seed[LSEED];
  Integer *state = 0;
  double *x = 0;
  char cgenid[40];
  /* Nag types */
  Nag_BaseRNG genid;
  NagError fail;

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

  printf("nag_rand_init_skipahead_power2 (g05kkc) Example Program Results\n\n");

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

  /* Read in the base generator information and seed */
  scanf("%39s%" NAG_IFMT "%" NAG_IFMT "%*[^\n] ", cgenid, &subid, &seed[0]);
  genid = (Nag_BaseRNG)nag_enum_name_to_value(cgenid);

  /* Query to get the require length of 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;
  }

  /* Allocate state */
  if (!(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 = 2;
    goto END;
  }

  /* Read in the skip ahead and sample size */
  scanf("%" NAG_IFMT "%" NAG_IFMT "%*[^\n] ", &n, &nv);
  if (!(x = NAG_ALLOC((nv), double))) {
    printf("Allocation failure\n");
    exit_status = -2;
    goto END;
  }

  /* Advance the sequence 2**n places */
  nag_rand_init_skipahead_power2(n, state, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_rand_init_skipahead_power2 (g05kkc).\n%s\n",
           fail.message);
    exit_status = 3;
    goto END;
  }

  /* Generate NV variates from a uniform distribution */
  nag_rand_dist_uniform01(nv, state, x, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_rand_dist_uniform01 (g05sac).\n%s\n", fail.message);
    exit_status = 4;
    goto END;
  }

  /* Display the variates */
  for (i = 0; i < nv; i++)
    printf("%10.4f\n", x[i]);
  printf("\n");

END:
  NAG_FREE(x);
  NAG_FREE(state);
  return exit_status;
}