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

#include <stdio.h>
#include <nag.h>
#include <nagx04.h>
#include <nag_stdlib.h>
#include <nagf07.h>
#include <nagf16.h>
#include <nagx02.h>
#include <math.h>

int main(int argc, char *argv[])
{
  FILE          *fpin, *fpout;

  /* 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);

  /* Check for command-line IO options */
  fpin = nag_example_file_io(argc, argv, "-data", NULL);
  fpout = nag_example_file_io(argc, argv, "-results", NULL);
  fprintf(fpout, "nag_dgecon (f07agc) Example Program Results\n");
  /* Skip heading in data file */
  fscanf(fpin, "%*[^\n] ");
  fscanf(fpin, "%ld%*[^\n] ", &n);
  pda = n;
  ipiv_len = n;

  /* Allocate memory */
  if (!(a = NAG_ALLOC(n * n, double)) ||
      !(ipiv = NAG_ALLOC(ipiv_len, Integer)))
    {
      fprintf(fpout, "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)
        fscanf(fpin, "%lf", &A(i, j));
    }
  fscanf(fpin, "%*[^\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)
    {
      fprintf(fpout, "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)
    {
      fprintf(fpout, "Error from nag_dgetrf (f07adc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }

  fprintf(fpout, "\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)
    {
      fprintf(fpout, "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)
    {
      fprintf(fpout, "Estimate of condition number =%11.2e\n", 1.0/rcond);
    }
  else
    fprintf(fpout, "A is singular to working precision\n");
 END:
  if (fpin != stdin) fclose(fpin);
  if (fpout != stdout) fclose(fpout);
  if (a) NAG_FREE(a);
  if (ipiv) NAG_FREE(ipiv);
  return exit_status;
}