/* nag_dtbsv (f16pkc) Example Program.
 *
 * Copyright 2005 Numerical Algorithms Group.
 *
 * Mark 8, 2005.
 */

#include <stdio.h>
#include <nag.h>
#include <nag_stdlib.h>
#include <nagf16.h>
#include <nagx04.h>

int main(int argc, char *argv[])
{
  FILE          *fpin, *fpout;

  /* Scalars */
  double        alpha;
  Integer       exit_status, i, incx, j, kd, n, pdab, xlen;

  /* Arrays */
  double        *ab = 0, *x = 0;
  char          nag_enum_arg[40];

  /* Nag Types */
  NagError      fail;
  Nag_OrderType order;
  Nag_TransType trans;
  Nag_UploType  uplo;
  Nag_DiagType  diag;

#ifdef NAG_COLUMN_MAJOR
#define AB_UPPER(I, J) ab[(J-1)*pdab + kd + I - J]
#define AB_LOWER(I, J) ab[(J-1)*pdab + I - J]
#define B(I, J)        b[(J-1)*pdb + I - 1]
  order = Nag_ColMajor;
#else
#define AB_UPPER(I, J) ab[(I-1)*pdab + J - I]
#define AB_LOWER(I, J) ab[(I-1)*pdab + kd + J - I]
#define B(I, J)        b[(I-1)*pdb + J - 1]
  order = Nag_RowMajor;
#endif

  exit_status = 0;
  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);

  fprintf(fpout, "nag_dtbsv (f16pkc) Example Program Results\n\n");

  /* Skip heading in data file */
  fscanf(fpin, "%*[^\n] ");

  /* Read the problem dimensions */
  fscanf(fpin, "%ld%ld%*[^\n] ", &n, &kd);

  /* Read the uplo storage parameter */
  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);
  /* Read the transpose parameter */
  fscanf(fpin, "%s%*[^\n] ", nag_enum_arg);
  /* nag_enum_name_to_value(x04nac), see above. */
  trans = (Nag_TransType) nag_enum_name_to_value(nag_enum_arg);
  /* Read the unit-diagonal parameter */
  fscanf(fpin, "%s%*[^\n] ", nag_enum_arg);
  /* nag_enum_name_to_value(x04nac), see above. */
  diag = (Nag_DiagType) nag_enum_name_to_value(nag_enum_arg);

  /* Read scalar parameters */
  fscanf(fpin, "%lf%*[^\n] ", &alpha);
  /* Read increment parameter */
  fscanf(fpin, "%ld%*[^\n] ", &incx);

  pdab = kd + 1;
  xlen = MAX(1, 1 + (n - 1)*ABS(incx));

  if (n > 0)
    {
      /* Allocate memory */
      if (!(ab = NAG_ALLOC(pdab*n, double)) ||
          !(x = NAG_ALLOC(xlen, double)))
        {
          fprintf(fpout, "Allocation failure\n");
          exit_status = -1;
          goto END;
        }
    }
  else
    {
      fprintf(fpout, "Invalid n\n");
      exit_status = 1;
      return exit_status;
    }

  /* Input matrix AB and vector x*/

  if (uplo == Nag_Upper)
    {
      for (i = 1; i <= n; ++i)
        {
          if (diag == Nag_NonUnitDiag)
            fscanf(fpin, "%lf", &AB_UPPER(i, i));
          for (j = i+1; j <= MIN(i+kd, n); ++j)
            fscanf(fpin, "%lf", &AB_UPPER(i, j));
        }
      fscanf(fpin, "%*[^\n] ");
    }
  else
    {
      for (i = 1; i <= n; ++i)
        {
          for (j = MAX(1, i-kd); j < i; ++j)
            fscanf(fpin, "%lf", &AB_LOWER(i, j));
          if (diag == Nag_NonUnitDiag)
            fscanf(fpin, "%lf", &AB_LOWER(i, i));
        }
      fscanf(fpin, "%*[^\n] ");
    }
  for (i = 0; i < xlen; ++i)
    fscanf(fpin, "%lf%*[^\n] ", &x[i]);

  /* nag_dtbsv(f16pkc).
   * Solution of real triangular band system of linear equations.
   *
   */
  nag_dtbsv(order, uplo, trans, diag, n, kd, alpha, ab, pdab, x, incx,
            &fail);
  if (fail.code != NE_NOERROR)
    {
      fprintf(fpout, "Error from nag_dtbsv.\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }

  /* Print output vector x */
  fprintf(fpout, "%s\n", " Solution x:");
  for (i = 0; i < xlen; ++i)
    {
      fprintf(fpout, "%11f\n", x[i]);
    }

 END:
  if (fpin != stdin) fclose(fpin);
  if (fpout != stdout) fclose(fpout);
  if (ab) NAG_FREE(ab);
  if (x) NAG_FREE(x);

  return exit_status;
}