/* nag_sort_reorder_vector (m01esc) Example Program.
 *
 * Copyright 2023 Numerical Algorithms Group.
 *
 * Mark 29.2, 2023.
 */

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

#ifdef __cplusplus
extern "C" {
#endif
static Integer NAG_CALL compare(const Nag_Pointer a, const Nag_Pointer b);
#ifdef __cplusplus
}
#endif

#define A(I, J) a[(I)*tda + J]
int main(void) {
  Integer exit_status = 0, tda;
  NagError fail;
  double *a = 0;
  size_t i, *indices = 0, j, k, m, n;

  INIT_FAIL(fail);

  /* Skip heading in data file */
  scanf("%*[^\n]");
  printf("nag_sort_reorder_vector (m01esc) Example Program Results\n");
  scanf("%" NAG_UFMT "%" NAG_UFMT "%" NAG_UFMT, &m, &n, &k);
  if (m >= 1 && n >= 1 && k >= 1 && k <= n) {
    if (!(a = NAG_ALLOC(m * n, double)) || !(indices = NAG_ALLOC(m, size_t))) {
      printf("Allocation failure\n");
      exit_status = -1;
      goto END;
    }
    tda = n;
  } else {
    printf("Invalid m or n or k.\n");
    exit_status = 1;
    return exit_status;
  }
  for (i = 0; i < m; ++i)
    for (j = 0; j < n; ++j)
      scanf("%lf", &A(i, j));
  /* nag_sort_rank_sort (m01dsc).
   * Rank sort of set of values of arbitrary data type
   */
  nag_sort_rank_sort((Pointer)&A(0, k - 1), m, (ptrdiff_t)(n * sizeof(double)),
                     compare, Nag_Ascending, indices, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_sort_rank_sort (m01dsc).\n%s\n", fail.message);
    exit_status = 1;
    goto END;
  }
  /* nag_sort_permute_invert (m01zac).
   * Inverts a permutation converting a rank vector to an
   * index vector or vice versa
   */
  nag_sort_permute_invert(indices, m, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_sort_permute_invert (m01zac).\n%s\n", fail.message);
    exit_status = 1;
    goto END;
  }
  for (j = 0; j < n; ++j) {
    /* nag_sort_reorder_vector (m01esc).
     * Reorders set of values of arbitrary data type into the
     * order specified by a set of indices
     */
    nag_sort_reorder_vector((Pointer)&A(0, j), m, sizeof(double),
                            (ptrdiff_t)(n * sizeof(double)), indices, &fail);
    if (fail.code != NE_NOERROR) {
      printf("Error from nag_sort_reorder_vector (m01esc).\n%s\n",
             fail.message);
      exit_status = 1;
      goto END;
    }
  }
  printf("\nMatrix with column %" NAG_UFMT " sorted\n", k);
  for (i = 0; i < m; ++i) {
    for (j = 0; j < n; ++j)
      printf("  %7.1f  ", A(i, j));
    printf("\n");
  }
END:
  NAG_FREE(a);
  NAG_FREE(indices);
  return exit_status;
}

static Integer NAG_CALL compare(const Nag_Pointer a, const Nag_Pointer b) {
  double x = *((const double *)a) - *((const double *)b);
  return (x < 0.0 ? -1 : (x == 0.0 ? 0 : 1));
}