/* nag_dsbmv (f16pdc) 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, beta;
  Integer       exit_status, i, incx, incy, j, k, kd, n, pdab, xlen, ylen;

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

  /* Nag Types */
  NagError      fail;
  Nag_OrderType order;
  Nag_UploType  uplo;

#ifdef NAG_COLUMN_MAJOR
#define AB_UPPER(I, J) ab[(J-1)*pdab + k + I - J - 1]
#define AB_LOWER(I, J) ab[(J-1)*pdab + I - J]
  order = Nag_ColMajor;
#else
#define AB_UPPER(I, J) ab[(I-1)*pdab + J - I]
#define AB_LOWER(I, J) ab[(I-1)*pdab + k + J - I - 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_dsbmv (f16pdc) Example Program Results\n\n");

  /* Skip heading in data file */
  fscanf(fpin, "%*[^\n] ");
  /* Read the problem dimension */
  fscanf(fpin, "%ld%ld%*[^\n] ", &n, &kd);
  /* Read uplo */
  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 scalar parameters */
  fscanf(fpin, "%lf%lf%*[^\n] ", &alpha, &beta);
  /* Read increment parameters */
  fscanf(fpin, "%ld%ld%*[^\n] ", &incx, &incy);

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

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

  /* Read A from data file */
  k = kd + 1;
  if (uplo == Nag_Upper)
    {
      for (i = 1; i <= n; ++i)
        {
          for (j = i; 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));
        }
      fscanf(fpin, "%*[^\n] ");
    }

  /* Input vectors x and y */

  for (i = 1; i <= xlen; ++i)
    fscanf(fpin, "%lf%*[^\n] ", &x[i - 1]);
  for (i = 1; i <= ylen; ++i)
    fscanf(fpin, "%lf%*[^\n] ", &y[i - 1]);

  /* nag_dsbmv(f16pdc).
   * Symmetric banded matrix-vector multiply.
   *
   */
  nag_dsbmv(order, uplo, n, kd, alpha, ab, pdab, x, incx,
            beta, y, incy, &fail);
  if (fail.code != NE_NOERROR)
    {
      fprintf(fpout, "Error from nag_dsbmv.\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }

  /* Print output vector y */
  fprintf(fpout, "%s\n", "  y");
  for (i = 1; i <= ylen; ++i)
    {
      fprintf(fpout, "%11f\n", y[i-1]);
    }

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

  return exit_status;
}