/* nag_rand_init_leapfrog (g05khc) Example Program.
 *
 * Copyright 2024 Numerical Algorithms Group.
 *
 * Mark 30.2, 2024.
 */
/* Pre-processor includes */
#include <math.h>
#include <nag.h>
#include <stdio.h>

#define STATE(I, J) state[(J - 1) * lstate + I - 1]

int main(void) {
  /* Integer scalar and array declarations */
  Integer exit_status = 0;
  Integer i, j, lstate;
  Integer *state = 0;
  /* NAG structures */
  NagError fail;
  /* Double scalar and array declarations */
  double *x = 0;
  /* Set the sample size */
  Integer nv = 5;
  /* Set the number of streams */
  Integer n = 3;
  /* 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_init_leapfrog (g05khc) Example Program Results\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;
  }

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

  /* Prepare n streams */
  for (i = 1; i <= n; i++) {
    /* Initialize the I'th stream to a repeatable sequence, using the same
       seed for each stream */
    nag_rand_init_repeat(genid, subid, seed, lseed, &STATE(1, i), &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;
    }

    /* Prepare the I'th out of N streams */
    nag_rand_init_leapfrog(n, i, &STATE(1, i), &fail);
    if (fail.code != NE_NOERROR) {
      printf("Error from nag_rand_init_leapfrog (g05khc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  }

  /* Loop over each of the n streams */
  for (i = 1; i <= n; i++) {
    /* Generate nv variates from a univariate distribution */
    printf(" Stream %12" NAG_IFMT "\n", i);
    nag_rand_dist_uniform01(nv, &STATE(1, i), x, &fail);
    if (fail.code != NE_NOERROR) {
      printf("Error from nag_rand_dist_uniform01 (g05sac).\n%s\n",
             fail.message);
      exit_status = 1;
      goto END;
    }

    /* Display the variates */
    for (j = 0; j < nv; j++)
      printf("%11.4f\n", x[j]);
    printf(" \n");
  }

END:
  NAG_FREE(x);
  NAG_FREE(state);

  return exit_status;
}