/* nag_real_eigenvalues (f02afc) Example Program.
 *
 * Copyright 1990 Numerical Algorithms Group.
 *
 * Mark 2 revised, 1992.
 * Mark 8 revised, 2004.
 */

#include <nag.h>
#include <stdio.h>
#include <nag_stdlib.h>
#include <nagf02.h>

#define COMPLEX(A) A.re, A.im
#define A(I,J) a[(I)*tda + J]

int main(void)
{
  Complex *r=0;
  Integer exit_status=0, i, *iter=0, j, n, tda;
  NagError fail;
  double *a=0;

  INIT_FAIL(fail);
  Vprintf("nag_real_eigenvalues (f02afc) Example Program Results\n");
  /* Skip heading in data file */
  Vscanf("%*[^\n]");
  Vscanf("%ld",&n);
  if (n>=1)
    {
      if ( !( a = NAG_ALLOC(n*n, double))  ||
           !( iter = NAG_ALLOC(n, Integer))  ||
           !( r = NAG_ALLOC(n, Complex)) )
        {
          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_eigenvalues (f02afc).
   * All eigenvalues of real matrix
   */
  nag_real_eigenvalues(n, a, tda, r, iter, &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from nag_real_eigenvalues (f02afc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }

  Vprintf("Eigenvalues\n");
  for (i=0; i<n; i++)
    Vprintf("( %7.3f ,  %7.3f ) \n", COMPLEX(r[i]));
 END:
  if (a) NAG_FREE(a);
  if (iter) NAG_FREE(iter);
  if (r) NAG_FREE(r);
  return exit_status;
}