/* nag_real_eigensystem_sel (f02ecc) Example Program.
 *
 * Copyright 1998 Numerical Algorithms Group.
 *
 * Mark 5, 1998.
 * Mark 8 revised, 2004.
 *
 */

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

#define MMAX 3
#define A(I, J) a[(I) *tda + J]
#define V(I, J) v[(I) *tdv + J]
int main(void)
{

  Complex  *v = 0, *w = 0;
  Integer  exit_status = 0, i, j, m, mest = MMAX, n, tda, tdv;
  double   *a = 0, wl, wu;

  NagError fail;

  INIT_FAIL(fail);

  printf(
          "nag_real_eigensystem_sel (f02ecc) Example Program Results\n\n");

  /* Skip heading in data file */
  scanf("%*[^\n]");
  mest = MMAX;
  scanf("%ld%lf%lf%*[^\n]", &n, &wl, &wu);

  if (n >= 0)
    {
      if (!(a = NAG_ALLOC(n*n, double)) ||
          !(w = NAG_ALLOC(n, Complex)) ||
          !(v = NAG_ALLOC(n*mest, Complex)))
        {
          printf("Allocation failure\n");
          exit_status = -1;
          goto END;
        }
      tda = n;
      tdv = mest;
    }
  else
    {
      printf("Invalid n.\n");
      exit_status = 1;
      return exit_status;
    }
  /* Read a from data file */
  for (i = 0; i < n; ++i)
    for (j = 0; j < n; ++j)
      scanf("%lf", &A(i, j));
  scanf("%*[^\n]");

  /* Compute selected eigenvalues and eigenvectors of A */

  /* nag_real_eigensystem_sel (f02ecc).
   * Computes selected eigenvalues and eigenvectors of a real
   * general matrix
   */
  nag_real_eigensystem_sel(Nag_Select_Modulus, n, a, tda, wl, wu, mest, &m, w,
                           v, tdv, &fail);
  if (fail.code != NE_NOERROR)
    {
      printf("Error from nag_real_eigensystem_sel (f02ecc).\n%s\n",
              fail.message);
      exit_status = 1;
      goto END;
    }

  printf("\n\nEigenvalues\n");
  for (i = 0; i < m; ++i)
    printf("(%7.4f, %7.4f)  ", w[i].re, w[i].im);
  printf("\n");


  printf(" Eigenvectors\n    ");
  for (i = 1; i <= m; i++)
    printf("%15ld%s", i, i%m == 0?"\n":"");
  for (i = 0; i < n; i++)
    {
      printf("%ld  ", i + 1);
      for (j = 0; j < m; j++)
        printf("(%8.4f, %8.4f)%s", V(i, j).re,
                V(i, j).im, (j + 1) % m == 0?"\n":"  ");
    }
 END:
  if (a) NAG_FREE(a);
  if (w) NAG_FREE(w);
  if (v) NAG_FREE(v);
  return exit_status;
}