/* nag_dsytrs (f07mec) Example Program.
 *
 * Copyright 2001 Numerical Algorithms Group.
 *
 * Mark 7, 2001.
 */

#include <stdio.h>
#include <nag.h>
#include <nag_stdlib.h>
#include <nagf07.h>
#include <nagx04.h>

int main(int argc, char *argv[])
{
  FILE          *fpin, *fpout;
  char          *outfile = 0;
  /* Scalars */
  Integer       i, j, n, nrhs, pda, pdb;
  Integer       exit_status = 0;
  NagError      fail;
  Nag_UploType  uplo;
  Nag_OrderType order;
  /* Arrays */
  char          nag_enum_arg[40];
  Integer       *ipiv = 0;
  double        *a = 0, *b = 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]
  order = Nag_ColMajor;
#else
#define A(I, J) a[(I-1)*pda + J - 1]
#define B(I, J) b[(I-1)*pdb + 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_dsytrs (f07mec) Example Program Results\n\n");
  /* Skip heading in data file */
  fscanf(fpin, "%*[^\n] ");
  fscanf(fpin, "%ld%ld%*[^\n] ", &n, &nrhs);
#ifdef NAG_COLUMN_MAJOR
  pda = n;
  pdb = n;
#else
  pda = n;
  pdb = nrhs;
#endif
  /* Allocate memory */
  if (!(ipiv = NAG_ALLOC(n, Integer)) ||
      !(a = NAG_ALLOC(n * n, double)) ||
      !(b = NAG_ALLOC(n * nrhs, double)))
    {
      fprintf(fpout, "Allocation failure\n");
      exit_status = -1;
      goto END;
    }

  /* Read A and B from data file */
  fscanf(fpin, " %s%*[^\n] ", nag_enum_arg);
  /* nag_enum_name_to_value(x04nac).
   * Converts NAG enum member name to value
   */
  uplo = (Nag_UploType) nag_enum_name_to_value(nag_enum_arg);

  if (uplo == Nag_Upper)
    {
      for (i = 1; i <= n; ++i)
        {
          for (j = i; j <= n; ++j)
            fscanf(fpin, "%lf", &A(i, j));
        }
      fscanf(fpin, "%*[^\n] ");
    }
  else
    {
      for (i = 1; i <= n; ++i)
        {
          for (j = 1; j <= i; ++j)
            fscanf(fpin, "%lf", &A(i, j));
        }
      fscanf(fpin, "%*[^\n] ");
    }

  for (i = 1; i <= n; ++i)
    {
      for (j = 1; j <= nrhs; ++j)
        fscanf(fpin, "%lf", &B(i, j));
    }
  fscanf(fpin, "%*[^\n] ");

  /* Factorize A */
  /* nag_dsytrf (f07mdc).
   * Bunch-Kaufman factorization of real symmetric indefinite
   * matrix
   */
  nag_dsytrf(order, uplo, n, a, pda, ipiv, &fail);
  if (fail.code != NE_NOERROR)
    {
      fprintf(fpout, "Error from nag_dsytrf (f07mdc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* Compute solution */
  /* nag_dsytrs (f07mec).
   * Solution of real symmetric indefinite system of linear
   * equations, multiple right-hand sides, matrix already
   * factorized by nag_dsytrf (f07mdc)
   */
  nag_dsytrs(order, uplo, n, nrhs, a, pda, ipiv, b, pdb,
             &fail);
  if (fail.code != NE_NOERROR)
    {
      fprintf(fpout, "Error from nag_dsytrs (f07mec).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* Print solution */
  /* 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, nrhs, b,
                         pdb, "Solution(s)", 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 (ipiv) NAG_FREE(ipiv);
  if (a) NAG_FREE(a);
  if (b) NAG_FREE(b);
  return exit_status;
}