/* nag_real_lu (f03afc) Example Program.
 *
 * Copyright 1990 Numerical Algorithms Group.
 *
 * Mark 2 revised, 1992.
 * Mark 8 revised, 2004.
 */

#include <nag.h>
#include <math.h>
#include <stdio.h>
#include <nag_stdlib.h>
#include <nagf03.h>

#define A(I,J) a[(I)*tda + J]

int main(void)
{
  Integer dete, exit_status=0, i, j, n, *pivot=0, tda;
  NagError fail;
  double *a=0, detf, two=2.0;

  INIT_FAIL(fail);
  Vprintf("nag_real_lu (f03afc) Example Program Results\n");
  /* Skip heading in data file */
  Vscanf("%*[^\n]");
  Vscanf("%ld",&n);

  if (n>=1)
    {
      if ( !( a = NAG_ALLOC(n*n, double))  ||
           !( pivot = NAG_ALLOC(n, Integer)) )
        {
          Vprintf("Allocation failure\n");
          exit_status = -1;
          goto END;
        }
      tda = n;
    }
  else
    {
      Vprintf("Invalid n.\n");
      exit_status = 1;
      return exit_status;
    }
  for (i=0; i<n; i++)
    for (j=0; j<n; j++)
      Vscanf("%lf",&A(i,j));
  /* nag_real_lu (f03afc).
   * LU factorization and determinant of real matrix
   */
  nag_real_lu(n, a, tda, pivot, &detf, &dete, &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from nag_real_lu (f03afc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  else
    {
      Vprintf("Array A after factorization\n");
      for (i=0; i<n; i++)
        for (j=0; j<n; j++)
          Vprintf("%9.4f%s",A(i,j),(j%8==7 || j==n-1) ? "\n" : " ");
      Vprintf("\nArray P\n");
      for (i=0; i<n; i++)
        Vprintf("%3ld%s",pivot[i],(i%8==7 || i==n-1) ? "\n" : " ");
      Vprintf("\ndetf = %9.4f  dete = %2ld\n", detf, dete);
      detf = detf * pow(two, (double)dete);
      Vprintf("\nValue of determinant = %9.4f\n", detf);
    }
 END:
  if (a) NAG_FREE(a);
  if (pivot) NAG_FREE(pivot);
  return exit_status;
}