/* nag_lapackeig_dorgqr (f08afc) Example Program.
 *
 * Copyright 2024 Numerical Algorithms Group.
 *
 * Mark 30.3, 2024.
 */

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

int main(void) {
  /* Scalars */
  Integer i, j, m, n, pda, tau_len;
  Integer exit_status = 0;
  NagError fail;
  Nag_OrderType order;
  /* Arrays */
  char *title = 0;
  double *a = 0, *tau = 0;

#ifdef NAG_COLUMN_MAJOR
#define A(I, J) a[(J - 1) * pda + I - 1]
  order = Nag_ColMajor;
#else
#define A(I, J) a[(I - 1) * pda + J - 1]
  order = Nag_RowMajor;
#endif

  INIT_FAIL(fail);

  printf("nag_lapackeig_dorgqr (f08afc) Example Program Results\n\n");

  /* Skip heading in data file */
  scanf("%*[^\n] ");
  scanf("%" NAG_IFMT "%" NAG_IFMT "%*[^\n] ", &m, &n);
#ifdef NAG_COLUMN_MAJOR
  pda = m;
#else
  pda = n;
#endif
  tau_len = MIN(m, n);

  /* Allocate memory */
  if (!(title = NAG_ALLOC(31, char)) || !(a = NAG_ALLOC(m * n, double)) ||
      !(tau = NAG_ALLOC(tau_len, double))) {
    printf("Allocation failure\n");
    exit_status = -1;
    goto END;
  }

  /* Read A from data file */
  for (i = 1; i <= m; ++i) {
    for (j = 1; j <= n; ++j)
      scanf("%lf", &A(i, j));
  }
  scanf("%*[^\n] ");

  /* Compute the QR factorization of A */
  /* nag_lapackeig_dgeqrf (f08aec).
   * QR factorization of real general rectangular matrix
   */
  nag_lapackeig_dgeqrf(order, m, n, a, pda, tau, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_lapackeig_dgeqrf (f08aec).\n%s\n", fail.message);
    exit_status = 1;
    goto END;
  }
  /* Form the leading N columns of Q explicitly */
  /* nag_lapackeig_dorgqr (f08afc).
   * Form all or part of orthogonal Q from QR factorization
   * determined by nag_lapackeig_dgeqrf (f08aec) or nag_lapackeig_dgeqpf
   * (f08bec)
   */
  nag_lapackeig_dorgqr(order, m, n, n, a, pda, tau, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_lapackeig_dorgqr (f08afc).\n%s\n", fail.message);
    exit_status = 1;
    goto END;
  }
  /* Print the leading N columns of Q only */
  sprintf(title, "The leading %2" NAG_IFMT " columns of Q\n", n);
  /* nag_file_print_matrix_real_gen (x04cac).
   * Print real general matrix (easy-to-use)
   */
  fflush(stdout);
  nag_file_print_matrix_real_gen(order, Nag_GeneralMatrix, Nag_NonUnitDiag, m,
                                 n, a, pda, title, 0, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_file_print_matrix_real_gen (x04cac).\n%s\n",
           fail.message);
    exit_status = 1;
    goto END;
  }

END:
  NAG_FREE(title);
  NAG_FREE(a);
  NAG_FREE(tau);

  return exit_status;
}