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

#include <nag.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(void)
{
  Nag_Boolean matz;
  Complex *alfa=0;
  Integer exit_status=0, i, ip, *iter=0, j, k, n, tda, tdb, tdz;
  NagError fail;
  double *a=0, *b=0, *beta=0, eps1, *z=0;

  INIT_FAIL(fail);
  Vprintf("nag_real_general_eigensystem (f02bjc) Example Program Results\n");
  Vscanf("%*[^\n]"); /* Skip heading in data file */
  Vscanf("%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)) )
        {
          Vprintf("Allocation failure\n");
          exit_status = -1;
          goto END;
        }
      tda = n;
      tdb = n;
      tdz = 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));
  for (i=0; i<n; ++i)
    for (j=0; j<n; ++j)
      Vscanf("%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)
    {
      Vprintf("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)
    {
      Vprintf("Eigensolution  %4ld\n",i+1);
      Vprintf("alfa[%ld].re %7.3f",i,alfa[i].re);
      Vprintf(" alfa[%ld].im %7.3f",i,alfa[i].im);
      Vprintf(" beta[%ld] %7.3f\n",i,beta[i]);
      if (beta[i] == 0.0)
        Vprintf("lambda is infinite");
      else
        if (alfa[i].im == 0.0)
          {
            Vprintf("lambda    %7.3f\n",alfa[i].re/beta[i]);
            Vprintf("Eigenvector\n");
            for (j=0; j<n; ++j)
              Vprintf("%7.3f\n", Z(j,i));
          }
        else
          {
            Vprintf("lambda    %7.3f   %7.3f\n",
                    alfa[i].re/beta[i], alfa[i].im/beta[i] );
            Vprintf("Eigenvector\n");
            k = (Integer)pow((double)-1, (double)(ip+2));
            for (j=0; j<n; ++j)
              {
                Vprintf("%7.3f",Z(j,i-ip));
                Vprintf("%7.3f\n",k*Z(j,i-ip+1));
              }
            ip = 1-ip;
          }
    }
  Vprintf("Number of iterations (machine-dependent)\n");
  for (i=0; i<n; ++i)
    Vprintf("%2ld",iter[i]);
  Vprintf("\n");
 END:
  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;
}