/* nag_dtrsen (f08qgc) 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, m, n, pdq, pdt, select_len, w_len;
  Integer  exit_status=0;
  double   s, sep;
  NagError fail;
  Nag_OrderType order;
  /* Arrays */
  double *q=0, *t=0, *wi=0, *wr=0;
  char   sel_char[2];
  Nag_Boolean *select=0;

#ifdef NAG_COLUMN_MAJOR
#define T(I,J) t[(J-1)*pdt + I - 1]
#define Q(I,J) q[(J-1)*pdq + I - 1]
  order = Nag_ColMajor;
#else
#define T(I,J) t[(I-1)*pdt + J - 1]
#define Q(I,J) q[(I-1)*pdq + J - 1]
  order = Nag_RowMajor;
#endif

  INIT_FAIL(fail);
  Vprintf("nag_dtrsen (f08qgc) Example Program Results\n\n");

  /* Skip heading in data file */
  Vscanf("%*[^\n] ");
  Vscanf("%ld%*[^\n] ", &n);
#ifdef NAG_COLUMN_MAJOR
  pdq = n;
  pdt = n;
#else
  pdq = n;
  pdt = n;
#endif
  w_len =n;
  select_len = n;

  /* Allocate memory */
  if ( !(q = NAG_ALLOC(n * n, double)) ||
       !(wi = NAG_ALLOC(w_len, double)) ||
       !(wr = NAG_ALLOC(w_len, double)) ||
       !(select = NAG_ALLOC(select_len, Nag_Boolean)) ||
       !(t = NAG_ALLOC(n * n, double)) )
    {
      Vprintf("Allocation failure\n");
      exit_status = -1;
      goto END;
    }

  /* Read T from data file */
  for (i = 1; i <= n; ++i)
    {
      for (j = 1; j <= n; ++j)
        Vscanf("%lf", &T(i,j));
    }
  Vscanf("%*[^\n] ");
  for (i = 1; i <= n; ++i)
    {
      for (j = 1; j <= n; ++j)
        Vscanf("%lf", &Q(i,j));
    }
  Vscanf("%*[^\n] ");
  for (i = 0; i < n; ++i)
    {
      Vscanf("  %1s ", sel_char);
      if (*(unsigned char *)sel_char == 'F')
        select[i] = Nag_FALSE;
      else
        select[i] = Nag_TRUE;
    }
  Vscanf("%*[^\n] ");

  /* Reorder the Schur factorization T */
  /* nag_dtrsen (f08qgc).
   * Reorder Schur factorization of real matrix, form
   * orthonormal basis of right invariant subspace for
   * selected eigenvalues, with estimates of sensitivities
   */
  nag_dtrsen(order, Nag_DoBoth, Nag_UpdateSchur, select, n, t, pdt,
             q, pdq, wr, wi, &m, &s, &sep, &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from nag_dtrsen (f08qgc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* Print reordered Schur form */
  /* nag_gen_real_mat_print (x04cac).
   * Print real general matrix (easy-to-use)
   */
  nag_gen_real_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, n,
                         t, pdt, "Reordered Schur form", 0, &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from nag_gen_real_mat_print (x04cac).\n%s\n",
              fail.message);
      exit_status = 1;
      goto END;
    }
  /* Print basis of invariant subspace */
  /* nag_gen_real_mat_print (x04cac), see above. */
  nag_gen_real_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, m, q,
                         pdq, "Basis of invariant subspace", 0, &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from nag_gen_real_mat_print (x04cac).\n%s\n",
              fail.message);
      exit_status = 1;
      goto END;
    }
  /* Print condition number estimates */
  Vprintf("\n Condition number estimate of the selected cluster of"
          " eigenvalues = %10.2e\n",1.0/s);
  Vprintf("\n Condition number estimate of the specified invariant"
          " subspace = %10.2e\n",1.0/sep);
 END:
  if (q) NAG_FREE(q);
  if (t) NAG_FREE(t);
  if (wi) NAG_FREE(wi);
  if (wr) NAG_FREE(wr);
  if (select) NAG_FREE(select);

  return exit_status;
}