/* nag_real_eigensystem (f02agc) Example Program.
 *
 * Copyright 1989 Numerical Algorithms Group.
 *
 * Mark 1, 1990.
 * 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]
#define V(I,J) v[(I)*tdv + J]

int main(void)
{

  Complex *r=0, *v=0;
  Integer exit_status=0, i, *iter=0, j, n, tda, tdv;
  NagError fail;
  double *a=0;

  INIT_FAIL(fail);
  Vprintf("nag_real_eigensystem (f02agc) 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)) ||
           !( v = NAG_ALLOC(n*n, Complex)) )
        {
          Vprintf("Allocation failure\n");
          exit_status = -1;
          goto END;
        }
      tda = n;
      tdv = 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_eigensystem (f02agc).
   * All eigenvalues and eigenvectors of real matrix
   */
  nag_real_eigensystem(n, a, tda, r, v, tdv, iter, &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from nag_real_eigensystem (f02agc).\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]));
  Vprintf("\nEigenvectors\n");
  for (i=0; i<n; i++)
    for (j=0; j<n; j++)
      Vprintf("(%7.3f, %7.3f) %s", COMPLEX(V(i,j)),
              (j%4==3 || j==n-1)? "\n" : " ");
 END:
  if (a) NAG_FREE(a);
  if (iter) NAG_FREE(iter);
  if (r) NAG_FREE(r);
  if (v) NAG_FREE(v);
  return exit_status;
}