/* nag_trans_hessenberg_observer (g13ewc)  Example Program.
 *
 * Copyright 1993 Numerical Algorithms Group
 *
 * Mark 3, 1993
 * Mark 8 revised, 2004.
 */

#include <nag.h>
#include <stdio.h>
#include <nag_stdlib.h>
#include <nagg13.h>

#define A(I,J) a[(I)*tda + J]
#define C(I,J) c[(I)*tdc + J]
#define U(I,J) u[(I)*tdu + J]
int main(void)
{
  Integer exit_status=0, i, j, n, p, tda, tdc, tdu;
  NagError fail;
  Nag_ObserverForm reduceto;
  double *a=0, *c=0, one=1.0, *u=0, zero=0.0;

  INIT_FAIL(fail);
  Vprintf("nag_trans_hessenberg_observer (g13ewc) Example Program Results\n");

  /* Skip the heading in the data file and read the data. */
  Vscanf("%*[^\n]");

  Vscanf("%ld%ld",&n,&p);
  if (n>=1 || p>=1)
    {
      if ( !( a = NAG_ALLOC(n*n, double)) ||
           !( c = NAG_ALLOC(p*n, double)) ||
           !( u = NAG_ALLOC(n*n, double)) )
        {
          Vprintf("Allocation failure\n");
          exit_status = -1;
          goto END;
        }
      tda = n;
      tdc = n;
      tdu = n;
    }
  else
    {
      Vprintf("Invalid n or p.\n");
      exit_status = 1;
      return exit_status;
    }

  reduceto = Nag_UH_Observer;

  for (j = 0; j < n; ++j)
    for (i = 0; i < n; ++i)
      Vscanf("%lf", &A(i,j));
  for (i = 0; i < p; ++i)
    for (j = 0; j < n; ++j)
      Vscanf("%lf", &C(i,j));

  if (u) /* Initialise U as the identity matrix. */
    for (i = 0; i < n; ++i)
      {
        for (j = 0; j < n; ++j)
          U(i,j) = zero;
        U(i,i) = one;
      }

  /* Reduce the pair (A,C) to reduceto observer Hessenberg form. */
  /* nag_trans_hessenberg_observer (g13ewc).
   * Unitary state-space transformation to reduce (AC) to
   * lower or upper observer Hessenberg form
   */
  nag_trans_hessenberg_observer(n, p, reduceto, a, tda, c, tdc, u, tdu,  &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from nag_trans_hessenberg_observer (g13ewc).\n%s\n",
              fail.message);
      exit_status = 1;
      goto END;
    }

  Vprintf("\nThe transformed state transition matrix is \n\n");
  for (i = 0; i < n; ++i)
    {
      for (j = 0; j < n; ++j)
        Vprintf("%8.4f ",A(i,j));
      Vprintf("\n");
    }
  Vprintf("\nThe transformed input matrix is \n\n");
  for (i = 0; i < p; ++i)
    {
      for (j = 0; j < n; ++j)
        Vprintf("%8.4f ",C(i,j));
      Vprintf("\n");
    }
  if (u)
    {
      Vprintf("\nThe transformation matrix that reduces (A,C) "
              "to observer Hessenberg form is \n\n");
      for (i = 0; i < n; ++i)
        {
          for (j = 0; j < n; ++j)
            Vprintf("%8.4f ",U(i,j));
          Vprintf("\n");
        }
    }
 END:
  if (a) NAG_FREE(a);
  if (c) NAG_FREE(c);
  if (u) NAG_FREE(u);
  return exit_status;
}