/* 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(void)
{

  /* 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);

  Vprintf( "nag_dtbsv (f16pkc) Example Program Results\n\n");

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

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

  /* Read the uplo storage parameter */
  Vscanf("%s%*[^\n] ", nag_enum_arg);
  /* nag_enum_name_to_value(x04nac).
   * Converts NAG enum member name to value
   */
  uplo = nag_enum_name_to_value(nag_enum_arg);
  /* Read the transpose parameter */
  Vscanf("%s%*[^\n] ", nag_enum_arg);
  /* nag_enum_name_to_value(x04nac), see above. */
  trans = nag_enum_name_to_value(nag_enum_arg);
  /* Read the unit-diagonal parameter */
  Vscanf("%s%*[^\n] ", nag_enum_arg);
  /* nag_enum_name_to_value(x04nac), see above. */
  diag = nag_enum_name_to_value(nag_enum_arg);

  /* Read scalar parameters */
  Vscanf("%lf%*[^\n] ", &alpha);
  /* Read increment parameter */
  Vscanf("%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)))
        {
          Vprintf("Allocation failure\n");
          exit_status = -1;
          goto END;
        }
    }
  else
    {
      Vprintf("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)
            Vscanf("%lf", &AB_UPPER(i,i));
          for (j = i+1; j <= MIN(i+kd,n); ++j)
            Vscanf("%lf", &AB_UPPER(i,j));
        }
      Vscanf("%*[^\n] ");
    }
  else
    {
      for (i = 1; i <= n; ++i)
        {
          for (j = MAX(1,i-kd); j < i; ++j)
            Vscanf("%lf", &AB_LOWER(i,j));
          if (diag == Nag_NonUnitDiag)
            Vscanf("%lf", &AB_LOWER(i,i));
        }
      Vscanf("%*[^\n] ");
    }
  for (i = 0; i < xlen; ++i)
    Vscanf("%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)
    {
      Vprintf("Error from nag_dtbsv.\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }

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

 END:
  if (ab) NAG_FREE(ab);
  if (x) NAG_FREE(x);

  return exit_status;
}