/* nag_dtrsyl (f08qhc) 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, m, n, pda, pdb, pdc;
  Integer       exit_status = 0;
  double        scale;
  NagError      fail;
  Nag_OrderType order;
  /* Arrays */
  double        *a = 0, *b = 0, *c = 0;

#ifdef NAG_COLUMN_MAJOR
#define A(I, J) a[(J-1)*pda + I - 1]
#define B(I, J) b[(J-1)*pdb + I - 1]
#define C(I, J) c[(J-1)*pdc + I - 1]
  order = Nag_ColMajor;
#else
#define A(I, J) a[(I-1)*pda + J - 1]
#define B(I, J) b[(I-1)*pdb + J - 1]
#define C(I, J) c[(I-1)*pdc + 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_dtrsyl (f08qhc) Example Program Results\n\n");

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

  /* Allocate memory */
  if (!(a = NAG_ALLOC(m * m, double)) ||
      !(b = NAG_ALLOC(n * m, double)) ||
      !(c = NAG_ALLOC(m * n, double)))
    {
      fprintf(fpout, "Allocation failure\n");
      exit_status = -1;
      goto END;
    }

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

  /* Reorder the Schur factorization T */
  /* nag_dtrsyl (f08qhc).
   * Solve real Sylvester matrix equation AX~+~XB~=~C, A and B
   * are upper quasi-triangular or transposes
   */
  nag_dtrsyl(order, Nag_NoTrans, Nag_NoTrans, Nag_Plus, m, n, a, pda,
             b, pdb, c, pdc, &scale, &fail);
  if (fail.code != NE_NOERROR)
    {
      fprintf(fpout, "Error from nag_dtrsyl (f08qhc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* Print the solution matrix X stored in C */
  /* 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, m, n,
                         c, pdc, "Solution matrix X", 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;
    }
  fprintf(fpout, "\n SCALE = %11.2e\n", scale);
 END:
  if (fpin != stdin) fclose(fpin);
  if (fpout != stdout) fclose(fpout);
  if (a) NAG_FREE(a);
  if (b) NAG_FREE(b);
  if (c) NAG_FREE(c);

  return exit_status;
}