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

#include <nag.h>
#include <nagx04.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(int argc, char *argv[])
{
  FILE             *fpin, *fpout;
  Integer          exit_status = 0, i, j, n, p, tda, tdc, tdu;
  double           *a = 0, *c = 0, one = 1.0, *u = 0, zero = 0.0;
  Nag_ObserverForm reduceto;
  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_trans_hessenberg_observer (g13ewc) Example Program Results\n");

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

  fscanf(fpin, "%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)))
        {
          fprintf(fpout, "Allocation failure\n");
          exit_status = -1;
          goto END;
        }
      tda = n;
      tdc = n;
      tdu = n;
    }
  else
    {
      fprintf(fpout, "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)
      fscanf(fpin, "%lf", &A(i, j));
  for (i = 0; i < p; ++i)
    for (j = 0; j < n; ++j)
      fscanf(fpin, "%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)
    {
      fprintf(fpout,
              "Error from nag_trans_hessenberg_observer (g13ewc).\n%s\n",
              fail.message);
      exit_status = 1;
      goto END;
    }

  fprintf(fpout, "\nThe transformed state transition matrix is \n\n");
  for (i = 0; i < n; ++i)
    {
      for (j = 0; j < n; ++j)
        fprintf(fpout, "%8.4f ", A(i, j));
      fprintf(fpout, "\n");
    }
  fprintf(fpout, "\nThe transformed input matrix is \n\n");
  for (i = 0; i < p; ++i)
    {
      for (j = 0; j < n; ++j)
        fprintf(fpout, "%8.4f ", C(i, j));
      fprintf(fpout, "\n");
    }
  if (u)
    {
      fprintf(fpout, "\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)
            fprintf(fpout, "%8.4f ", U(i, j));
          fprintf(fpout, "\n");
        }
    }
 END:
  if (fpin != stdin) fclose(fpin);
  if (fpout != stdout) fclose(fpout);
  if (a) NAG_FREE(a);
  if (c) NAG_FREE(c);
  if (u) NAG_FREE(u);
  return exit_status;
}