/* nag_dgecon (f07agc) Example Program.
 *
 * Copyright 2001 Numerical Algorithms Group.
 *
 * Mark 7, 2001.
 * Mark 7b revised, 2004.
 */

#include <stdio.h>
#include <nag.h>
#include <nag_stdlib.h>
#include <nagf07.h>
#include <nagf16.h>
#include <nagx02.h>
#include <math.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);
  Vprintf("nag_dgecon (f07agc) Example Program Results\n");
  /* Skip heading in data file */
  Vscanf("%*[^\n] ");
  Vscanf("%ld%*[^\n] ", &n);
  pda = n;
  ipiv_len = n;

  /* Allocate memory */
  if ( !(a = NAG_ALLOC(n * n, double)) ||
       !(ipiv = NAG_ALLOC(ipiv_len, Integer)) )
    {
      Vprintf("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)
        Vscanf("%lf", &A(i,j));
    }
  Vscanf("%*[^\n] ");

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

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

  Vprintf("\n");
  /* Estimate condition number */
  /* nag_dgecon (f07agc).
   * Estimate condition number of real matrix, matrix already
   * factorized by nag_dgetrf (f07adc)
   */
  nag_dgecon(order, Nag_OneNorm, n, a, pda, anorm, &rcond, &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from nag_dgecon (f07agc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* nag_machine_precision (x02ajc).
   * The machine precision
   */
  if (rcond >= X02AJC)
    {
      Vprintf("Estimate of condition number =%10.2e\n", 1.0/rcond);
    }
  else
    Vprintf("A is singular to working precision\n");
 END:
  if (a) NAG_FREE(a);
  if (ipiv) NAG_FREE(ipiv);
  return exit_status;
}