/* nag_dhseqr (f08pec) 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, j, n, pdh, pdz, wi_len, wr_len;
  Integer       exit_status = 0;
  NagError      fail;
  Nag_OrderType order;
  /* Arrays */
  double        *h = 0, *wi = 0, *wr = 0, *z = 0;

#ifdef NAG_COLUMN_MAJOR
#define H(I, J) h[(J-1)*pdh + I - 1]
  order = Nag_ColMajor;
#else
#define H(I, J) h[(I-1)*pdh + 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_dhseqr (f08pec) Example Program Results\n\n");

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

  /* Allocate memory */
  if (!(h = NAG_ALLOC(n * n, double)) ||
      !(wi = NAG_ALLOC(wi_len, double)) ||
      !(wr = NAG_ALLOC(wr_len, double)) ||
      !(z = NAG_ALLOC(n * n, double)))
    {
      fprintf(fpout, "Allocation failure\n");
      exit_status = -1;
      goto END;
    }

  /* Read H from data file */
  for (i = 1; i <= n; ++i)
    {
      for (j = 1; j <= n; ++j)
        fscanf(fpin, "%lf", &H(i, j));
    }
  fscanf(fpin, "%*[^\n] ");

  /* Calculate the eigenvalues and Schur factorization of H */
  /* nag_dhseqr (f08pec).
   * Eigenvalues and Schur factorization of real upper
   * Hessenberg matrix reduced from real general matrix
   */
  nag_dhseqr(order, Nag_Schur, Nag_InitZ, n, 1, n, h, pdh, wr,
             wi, z, pdz, &fail);
  if (fail.code != NE_NOERROR)
    {
      fprintf(fpout, "Error from nag_dhseqr (f08pec).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  fprintf(fpout, " Eigenvalues\n");
  for (i = 1; i <= n; ++i)
    fprintf(fpout, " (%8.4f,%8.4f)", wr[i-1], wi[i-1]);
  fprintf(fpout, "\n");

  /* Print 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,
                         h, pdh, "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;
    }
  /* Print Schur vectors */
  fprintf(fpout, "\n");
  /* nag_gen_real_mat_print (x04cac), see above. */
  if (outfile) fclose(fpout);
  nag_gen_real_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, n,
                         z, pdz, "Schur vectors of H", 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 (h) NAG_FREE(h);
  if (wi) NAG_FREE(wi);
  if (wr) NAG_FREE(wr);
  if (z) NAG_FREE(z);

  return exit_status;
}