/* nag_dtrexc (f08qfc) 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(int argc, char *argv[])
{
  FILE          *fpin, *fpout;
  char          *outfile = 0;
  /* Scalars */
  Integer       i, ifst, ilst, j, n, pdq, pdt;
  Integer       exit_status = 0;
  NagError      fail;
  Nag_OrderType order;
  /* Arrays */
  double        *q = 0, *t = 0;

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

  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);
  (void) nag_example_file_io(argc, argv, "-nag_write", &outfile);
  fprintf(fpout, "nag_dtrexc (f08qfc) Example Program Results\n\n");

  /* Skip heading in data file */
  fscanf(fpin, "%*[^\n] ");
  fscanf(fpin, "%ld%*[^\n] ", &n);
#ifdef NAG_COLUMN_MAJOR
  pdq = 1;
  pdt = n;
#else
  pdq = 1;
  pdt = n;
#endif

  /* Allocate memory */
  if (!(q = NAG_ALLOC(1 * 1, double)) ||
      !(t = NAG_ALLOC(n * n, double)))
    {
      fprintf(fpout, "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)
        fscanf(fpin, "%lf", &T(i, j));
    }
  fscanf(fpin, "%*[^\n] ");
  fscanf(fpin, "%ld%ld%*[^\n] ", &ifst, &ilst);

  /* Reorder the Schur factorization T */
  /* nag_dtrexc (f08qfc).
   * Reorder Schur factorization of real matrix using
   * orthogonal similarity transformation
   */
  nag_dtrexc(order, Nag_NotQ, n, t, pdt, q, pdq, &ifst, &ilst, &fail);
  if (fail.code != NE_NOERROR)
    {
      fprintf(fpout, "Error from nag_dtrexc (f08qfc).\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)
   */
  if (outfile) fclose(fpout);
  nag_gen_real_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, n,
                         t, pdt, "Reordered Schur form", outfile, &fail);
  if (outfile && !(fpout = fopen(outfile, "a")))
    {
      exit_status = 2;
      goto END;
    }
  if (fail.code != NE_NOERROR)
    {
      fprintf(fpout, "Error from nag_gen_real_mat_print (x04cac).\n%s\n",
              fail.message);
      exit_status = 1;
      goto END;
    }
 END:
  if (fpin != stdin) fclose(fpin);
  if (fpout != stdout) fclose(fpout);
  if (q) NAG_FREE(q);
  if (t) NAG_FREE(t);

  return exit_status;
}