/* nag_blast_dtbsv (f16pkc) Example Program.
 *
 * Copyright 2024 Numerical Algorithms Group.
 *
 * Mark 30.1, 2024.
 */

#include <nag.h>
#include <stdio.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]
  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]
  order = Nag_RowMajor;
#endif

  exit_status = 0;
  INIT_FAIL(fail);

  printf("nag_blast_dtbsv (f16pkc) Example Program Results\n\n");

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

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

  /* Read the uplo storage parameter */
  scanf("%39s%*[^\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 */
  scanf("%39s%*[^\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 */
  scanf("%39s%*[^\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 */
  scanf("%lf%*[^\n] ", &alpha);
  /* Read increment parameter */
  scanf("%" NAG_IFMT "%*[^\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))) {
      printf("Allocation failure\n");
      exit_status = -1;
      goto END;
    }
  } else {
    printf("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)
        scanf("%lf", &AB_UPPER(i, i));
      for (j = i + 1; j <= MIN(i + kd, n); ++j)
        scanf("%lf", &AB_UPPER(i, j));
    }
    scanf("%*[^\n] ");
  } else {
    for (i = 1; i <= n; ++i) {
      for (j = MAX(1, i - kd); j < i; ++j)
        scanf("%lf", &AB_LOWER(i, j));
      if (diag == Nag_NonUnitDiag)
        scanf("%lf", &AB_LOWER(i, i));
    }
    scanf("%*[^\n] ");
  }
  for (i = 0; i < xlen; ++i)
    scanf("%lf%*[^\n] ", &x[i]);

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

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

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

  return exit_status;
}