/* nag_blast_dgbmv (f16pbc) Example Program.
 *
 * Copyright 2024 Numerical Algorithms Group.
 *
 * Mark 30.0, 2024.
 */

#include <nag.h>
#include <stdio.h>

int main(void) {

  /* Scalars */
  double alpha, beta;
  Integer ab_size, exit_status, i, incx, incy, j, kl, ku;
  Integer m, 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_TransType trans;

#ifdef NAG_COLUMN_MAJOR
#define AB(I, J) ab[(J - 1) * pdab + ku + I - J]
  order = Nag_ColMajor;
#else
#define AB(I, J) ab[(I - 1) * pdab + kl + J - I]
  order = Nag_RowMajor;
#endif

  exit_status = 0;
  INIT_FAIL(fail);

  printf("nag_blast_dgbmv (f16pbc) Example Program Results\n\n");

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

  /* Read the problem dimensions */
  scanf("%" NAG_IFMT "%" NAG_IFMT "%" NAG_IFMT "%" NAG_IFMT "%*[^\n] ", &m, &n,
        &kl, &ku);
  /* Read the transpose parameter */
  scanf("%39s%*[^\n] ", nag_enum_arg);
  /* nag_enum_name_to_value (x04nac).
   * Converts NAG enum member name to value
   */
  trans = (Nag_TransType)nag_enum_name_to_value(nag_enum_arg);
  /* Read scalar parameters */
  scanf("%lf %lf%*[^\n] ", &alpha, &beta);
  /* Read increment parameters */
  scanf("%" NAG_IFMT "%" NAG_IFMT "%*[^\n] ", &incx, &incy);

  pdab = kl + ku + 1;
#ifdef NAG_COLUMN_MAJOR
  ab_size = pdab * n;
#else
  ab_size = pdab * m;
#endif

  if (trans == Nag_NoTrans) {
    xlen = MAX(1, 1 + (n - 1) * ABS(incx));
    ylen = MAX(1, 1 + (m - 1) * ABS(incy));
  } else {
    xlen = MAX(1, 1 + (m - 1) * ABS(incx));
    ylen = MAX(1, 1 + (n - 1) * ABS(incy));
  }

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

  /* Input matrix A and vectors x and y */

  for (i = 1; i <= m; ++i) {
    for (j = MAX(1, i - kl); j <= MIN(n, i + ku); ++j)
      scanf("%lf", &AB(i, j));
    scanf("%*[^\n] ");
  }
  for (i = 1; i <= xlen; ++i)
    scanf("%lf%*[^\n] ", &x[i - 1]);
  for (i = 1; i <= ylen; ++i)
    scanf("%lf%*[^\n] ", &y[i - 1]);

  /* nag_blast_dgbmv (f16pbc).
   * real valued band matrix-vector multiply.
   *
   */
  nag_blast_dgbmv(order, trans, m, n, kl, ku, alpha, ab, pdab, x, incx, beta, y,
                  incy, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_blast_dgbmv.\n%s\n", fail.message);
    exit_status = 1;
    goto END;
  }

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

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

  return exit_status;
}