/* nag_dorghr (f08nfc) Example Program.
 *
 * Copyright 2001 Numerical Algorithms Group.
 *
 * Mark 7, 2001.
*/

#include <stdio.h>
#include <nag.h>
#include <nag_stdlib.h>
#include <nagf08.h>
#include <nagx04.h>

int main(void)
{
/* Scalars */
  Integer  i, j, n, pda, pdz, tau_len, wr_len, wi_len;
  Integer  exit_status=0;
  NagError fail;
  Nag_OrderType order;
/* Arrays */
  double *a=0, *tau=0, *wi=0, *wr=0, *z=0;

#ifdef NAG_COLUMN_MAJOR
#define A(I,J) a[(J-1)*pda + I - 1]
#define Z(I,J) z[(J-1)*pdz + I - 1]
  order = Nag_ColMajor;
#else
#define A(I,J) a[(I-1)*pda + J - 1]
#define Z(I,J) z[(I-1)*pdz + J - 1]
  order = Nag_RowMajor;
#endif

  INIT_FAIL(fail);
  Vprintf("f08nfc Example Program Results\n\n");

/* Skip heading in data file */
  Vscanf("%*[^\n] ");
  Vscanf("%ld%*[^\n] ", &n);
#ifdef NAG_COLUMN_MAJOR
  pda = n;
  pdz = n;
#else
  pda = n;
  pdz = n;
#endif
  tau_len = n - 1;
  wr_len = n;
  wi_len = n;

  /* Allocate memory */
  if ( !(a = NAG_ALLOC(n * n, double)) ||
       !(tau = NAG_ALLOC(tau_len, double)) ||
       !(wi = NAG_ALLOC(wi_len, double)) ||
       !(wr = NAG_ALLOC(wi_len, double)) ||
       !(z = NAG_ALLOC(n * n, double)) )
    {
      Vprintf("Allocation failure\n");
      exit_status = -1;
      goto END;
    }

  /* Read A from data file */
  for (i = 1; i <= n; ++i)
    {
      for (j = 1; j <= n; ++j)
        Vscanf("%lf", &A(i,j));
    }
  Vscanf("%*[^\n] ");

  /* Reduce A to upper Hessenberg form H = (Q**T)*A*Q */
  f08nec(order, n, 1, n, a, pda, tau, &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from f08nec.\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }

  /* Copy A into Z */
  for (i = 1; i <= n; ++i)
    {
      for (j = 1; j <= n; ++j)
        Z(i,j) = A(i,j);
    }

  /* Form Q explicitly, storing the result in Z */
  f08nfc(order, n, 1, n, z, pdz, tau, &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from f08nfc.\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }

  /* Calculate the Schur factorization of H = Y*T*(Y**T) and form */
  /* Q*Y explicitly, storing the result in Z */

  /* Note that A = Z*T*(Z**T), where Z = Q*Y */
  f08pec(order, Nag_Schur, Nag_UpdateZ, n, 1, n, a, pda,
         wr, wi, z, pdz, &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from f08pec.\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }

  /* Print Schur form */

  x04cac(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, n,
         a, pda, "Schur form", 0, &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from x04cac.\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }

  /* Print Schur vectors */
  Vprintf("\n");
  x04cac(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, n,
         z, pdz, "Schur vectors of A", 0, &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from x04cac.\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
 END:
  if (a) NAG_FREE(a);
  if (tau) NAG_FREE(tau);
  if (wi) NAG_FREE(wi);
  if (wr) NAG_FREE(wr);
  if (z) NAG_FREE(z);

  return exit_status;
}