/* nag_lapacklin_dgecon (f07agc) Example Program.
 *
 * Copyright 2024 Numerical Algorithms Group.
 *
 * Mark 30.3, 2024.
 */

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

int main(void) {

  /* Scalars */
  double anorm, rcond;
  Integer exit_status = 0;
  Integer i, ipiv_len, j, n, pda;
  NagError fail;
  Nag_OrderType order;

  /* Arrays */
  double *a = 0;
  Integer *ipiv = 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_lapacklin_dgecon (f07agc) Example Program Results\n");
  /* Skip heading in data file */
  scanf("%*[^\n] ");
  scanf("%" NAG_IFMT "%*[^\n] ", &n);
  pda = n;
  ipiv_len = n;

  /* Allocate memory */
  if (!(a = NAG_ALLOC(n * n, double)) ||
      !(ipiv = NAG_ALLOC(ipiv_len, Integer))) {
    printf("Allocation failure\n");
    exit_status = -1;
    goto END;
  }

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

  /* Compute norm of A */
  /* nag_blast_dge_norm (f16rac).
   * 1-norm, infinity-norm, Frobenius norm, largest absolute
   * element, real general matrix
   */
  nag_blast_dge_norm(order, Nag_OneNorm, n, n, a, pda, &anorm, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_blast_dge_norm (f16rac).\n%s\n", fail.message);
    exit_status = 1;
    goto END;
  }

  /* Factorize A */
  /* nag_lapacklin_dgetrf (f07adc).
   * LU factorization of real m by n matrix
   */
  nag_lapacklin_dgetrf(order, n, n, a, pda, ipiv, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_lapacklin_dgetrf (f07adc).\n%s\n", fail.message);
    exit_status = 1;
    goto END;
  }

  printf("\n");
  /* Estimate condition number */
  /* nag_lapacklin_dgecon (f07agc).
   * Estimate condition number of real matrix, matrix already
   * factorized by nag_lapacklin_dgetrf (f07adc)
   */
  nag_lapacklin_dgecon(order, Nag_OneNorm, n, a, pda, anorm, &rcond, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_lapacklin_dgecon (f07agc).\n%s\n", fail.message);
    exit_status = 1;
    goto END;
  }
  /* nag_machine_precision (x02ajc).
   * The machine precision
   */
  if (rcond >= nag_machine_precision) {
    printf("Estimate of condition number =%11.2e\n", 1.0 / rcond);
  } else
    printf("A is singular to working precision\n");
END:
  NAG_FREE(a);
  NAG_FREE(ipiv);
  return exit_status;
}