/* nag_trans_hessenberg_controller (g13exc)  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 B(I,J) b[(I)*tdb + J]
#define U(I,J) u[(I)*tdu + J]
int main(void)
{
  Integer exit_status=0, i, j, m, n, tda, tdb, tdu;
  NagError fail;
  Nag_ControllerForm reduceto;
  double *a=0, *b=0, one=1.0, *u=0, zero=0.0;

  INIT_FAIL(fail);

  Vprintf("nag_trans_hessenberg_controller (g13exc) Example Program Results\n");

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

  Vscanf("%ld%ld",&n,&m);
  if (n>=1 || m>=1)
    {
      if ( !( a = NAG_ALLOC(n*n, double)) ||
           !( b = NAG_ALLOC(n*m, double)) ||
           !( u = NAG_ALLOC(n*n, double)) )
        {
          Vprintf("Allocation failure\n");
          exit_status = -1;
          goto END;
        }
      tda = n;
      tdb = m;
      tdu = n;

    }
  else
    {
      Vprintf("Invalid n or m.\n");
      exit_status = 1;
      return exit_status;
    }
  reduceto = Nag_UH_Controller;

  for (j=0; j<n; ++j)
    for (i=0; i<n; ++i)
      Vscanf("%lf",&A(i,j));
  for (j=0; j<m; ++j)
    for (i=0; i<n; ++i)
      Vscanf("%lf",&B(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 (B,A) to reduceto controller Hessenberg form. */
  /* nag_trans_hessenberg_controller (g13exc).
   * Unitary state-space transformation to reduce (BA) to
   * lower or upper controller Hessenberg form
   */
  nag_trans_hessenberg_controller(n, m,  reduceto, a, tda, b, tdb, u, tdu,
                                  &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from nag_trans_hessenberg_controller (g13exc).\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<n; ++i)
    {
      for (j=0; j<m; ++j)
        Vprintf("%8.4f ", B(i,j));
      Vprintf("\n");
    }
  if (u)
    {
      Vprintf("\nThe matrix that reduces (B,A) to ");
      Vprintf("controller 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 (b) NAG_FREE(b);
  if (u) NAG_FREE(u);
  return exit_status;

}