/* nag_rand_matrix_orthog (g05pxc) Example Program.
 *
 * Copyright 2024 Numerical Algorithms Group.
 *
 * Mark 30.3, 2024.
 */
/* Pre-processor includes */
#include <math.h>
#include <nag.h>
#include <stdio.h>

#define A(I, J) a[I * pda + J]

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

  /* NAG structures */
  NagError fail;

  /* Double scalar and array declarations */
  double *a = 0;

  /* Set the size of the matrix to be generated */
  Integer n = 4;
  Integer m = 4;

  /* Set A to the identity matrix on input */
  Nag_InitializeA init = Nag_InitializeI;

  /* Multiple on the right hand side */
  Nag_SideType side = Nag_RightSide;

  /* 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_matrix_orthog (g05pxc) 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;
  }

  pda = n;
  a_size = pda * m;

  /* Allocate arrays */
  if (!(a = NAG_ALLOC(a_size, 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 random orthogonal matrix */
  nag_rand_matrix_orthog(side, init, m, n, state, a, pda, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_rand_matrix_orthog (g05pxc).\n%s\n", fail.message);
    exit_status = 1;
    goto END;
  }

  /* Display the results */
  for (i = 0; i < m; i++) {
    printf("  ");
    for (j = 0; j < n; j++)
      printf("%8.3f%s", A(i, j), (j + 1) % 4 ? " " : "\n");
    if (n % 4)
      printf("\n");
  }

END:
  NAG_FREE(a);
  NAG_FREE(state);

  return exit_status;
}