/* nag_real_general_eigensystem (f02bjc) Example Program.
 *
 * Copyright 1991 Numerical Algorithms Group.
 *
 * Mark 2, 1991.
 * Mark 8 revised, 2004.
 */

#include <nag.h>
#include <nagx04.h>
#include <stdio.h>
#include <nag_stdlib.h>
#include <math.h>
#include <nagf02.h>
#include <nagx02.h>

#define A(I, J) a[(I) *tda + J]
#define B(I, J) b[(I) *tdb + J]
#define Z(I, J) z[(I) *tdz + J]

int main(int argc, char *argv[])
{
  FILE        *fpin, *fpout;
  Nag_Boolean matz;
  Complex     *alfa = 0;
  Integer     exit_status = 0, i, ip, *iter = 0, j, k, n, tda, tdb, tdz;
  double      *a = 0, *b = 0, *beta = 0, eps1, *z = 0;
  NagError    fail;

  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_real_general_eigensystem (f02bjc) Example Program Results\n");
  fscanf(fpin, "%*[^\n]"); /* Skip heading in data file */
  fscanf(fpin, "%ld", &n);
  if (n >= 1)
    {
      if (!(beta = NAG_ALLOC(n, double)) ||
          !(a = NAG_ALLOC(n*n, double)) ||
          !(b = NAG_ALLOC(n*n, double)) ||
          !(z = NAG_ALLOC(n*n, double)) ||
          !(iter = NAG_ALLOC(n, Integer)) ||
          !(alfa = NAG_ALLOC(n, Complex)))
        {
          fprintf(fpout, "Allocation failure\n");
          exit_status = -1;
          goto END;
        }
      tda = n;
      tdb = n;
      tdz = n;
    }
  else
    {
      fprintf(fpout, "Invalid n.\n");
      exit_status = 1;
      return exit_status;
    }
  for (i = 0; i < n; ++i)
    for (j = 0; j < n; ++j)
      fscanf(fpin, "%lf", &A(i, j));
  for (i = 0; i < n; ++i)
    for (j = 0; j < n; ++j)
      fscanf(fpin, "%lf", &B(i, j));
  matz = Nag_TRUE;
  /* nag_machine_precision (x02ajc).
   * The machine precision
   */
  eps1 = X02AJC;
  /* nag_real_general_eigensystem (f02bjc).
   * All eigenvalues and optionally eigenvectors of real
   * generalized eigenproblem, by QZ algorithm
   */
  nag_real_general_eigensystem(n, a, tda, b, tdb, eps1,
                               alfa, beta, matz, z, tdz, iter,
                               &fail);
  if (fail.code != NE_NOERROR)
    {
      fprintf(fpout, "Error from nag_real_general_eigensystem (f02bjc).\n%s\n",
              fail.message);
      exit_status = 1;
      goto END;
    }

  ip = 0;
  for (i = 0; i < n; ++i)
    {
      fprintf(fpout, "Eigensolution  %4ld\n", i+1);
      fprintf(fpout, "alfa[%ld].re %7.3f", i, alfa[i].re);
      fprintf(fpout, " alfa[%ld].im %7.3f", i, alfa[i].im);
      fprintf(fpout, " beta[%ld] %7.3f\n", i, beta[i]);
      if (beta[i] == 0.0)
        fprintf(fpout, "lambda is infinite");
      else
      if (alfa[i].im == 0.0)
        {
          fprintf(fpout, "lambda    %7.3f\n", alfa[i].re/beta[i]);
          fprintf(fpout, "Eigenvector\n");
          for (j = 0; j < n; ++j)
            fprintf(fpout, "%7.3f\n", Z(j, i));
        }
      else
        {
          fprintf(fpout, "lambda    %7.3f   %7.3f\n",
                  alfa[i].re/beta[i], alfa[i].im/beta[i]);
          fprintf(fpout, "Eigenvector\n");
          k = (Integer) pow((double) -1, (double)(ip+2));
          for (j = 0; j < n; ++j)
            {
              fprintf(fpout, "%7.3f", Z(j, i-ip));
              fprintf(fpout, "%7.3f\n", k*Z(j, i-ip+1));
            }
          ip = 1-ip;
        }
    }
  fprintf(fpout, "Number of iterations (machine-dependent)\n");
  for (i = 0; i < n; ++i)
    fprintf(fpout, "%2ld", iter[i]);
  fprintf(fpout, "\n");
 END:
  if (fpin != stdin) fclose(fpin);
  if (fpout != stdout) fclose(fpout);
  if (beta) NAG_FREE(beta);
  if (a) NAG_FREE(a);
  if (b) NAG_FREE(b);
  if (z) NAG_FREE(z);
  if (iter) NAG_FREE(iter);
  if (alfa) NAG_FREE(alfa);
  return exit_status;
}