/* nag_lapacklin_dpbsv (f07hac) Example Program.
 *
 * Copyright 2024 Numerical Algorithms Group.
 *
 * Mark 30.3, 2024.
 */
#include <nag.h>
#include <stdio.h>

int main(void) {

  /* Scalars */
  Integer exit_status = 0, i, j, kd, n, nrhs, pdb, pdab;

  /* Arrays */
  double *ab = 0, *b = 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 + 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

  INIT_FAIL(fail);

  printf("nag_lapacklin_dpbsv (f07hac) Example Program Results\n\n");

  /* Skip heading in data file */
  scanf("%*[^\n]");
  scanf("%" NAG_IFMT "%" NAG_IFMT "%" NAG_IFMT "%*[^\n]", &n, &kd, &nrhs);
  if (n < 0 || nrhs < 0 || kd < 0) {
    printf("Invalid n, kd or nrhs\n");
    exit_status = 1;
    goto END;
  }
  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);

  /* Allocate memory */
  if (!(ab = NAG_ALLOC((kd + 1) * n, double)) ||
      !(b = NAG_ALLOC(n * nrhs, double))) {
    printf("Allocation failure\n");
    exit_status = -1;
    goto END;
  }

  pdab = kd + 1;
#ifdef NAG_COLUMN_MAJOR
  pdb = n;
#else
  pdb = nrhs;
#endif

  /* Read the upper or lower triangular part of the band matrix A from
   * data file.
   */
  if (uplo == Nag_Upper)
    for (i = 1; i <= n; ++i)
      for (j = i; j <= MIN(n, i + kd); ++j)
        scanf("%lf", &AB_UPPER(i, j));
  else
    for (i = 1; i <= n; ++i)
      for (j = MAX(1, i - kd); j <= i; ++j)
        scanf("%lf", &AB_LOWER(i, j));
  scanf("%*[^\n]");

  /* Read b from data file */
  for (i = 1; i <= n; ++i)
    for (j = 1; j <= nrhs; ++j)
      scanf("%lf", &B(i, j));
  scanf("%*[^\n]");

  /* Solve the equations Ax = b for x using nag_lapacklin_dpbsv (f07hac). */
  nag_lapacklin_dpbsv(order, uplo, n, kd, nrhs, ab, pdab, b, pdb, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_lapacklin_dpbsv (f07hac).\n%s\n", fail.message);
    exit_status = 1;
    goto END;
  }
  /* Print solution */
  printf("Solution\n");
  for (i = 1; i <= n; ++i) {
    for (j = 1; j <= nrhs; ++j)
      printf("%11.4f%s", B(i, j), j % 7 == 0 ? "\n" : " ");
    printf("\n");
  }

  /* Print details of factorization */
  printf("\n");
  fflush(stdout);
  if (uplo == Nag_Upper)
    nag_file_print_matrix_real_band(order, n, n, 0, kd, ab, pdab,
                                    "Cholesky factor U", 0, &fail);
  else
    nag_file_print_matrix_real_band(order, n, n, kd, 0, ab, pdab,
                                    "Cholesky factor L", 0, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_file_print_matrix_real_band (x04cec).\n%s\n",
           fail.message);
    exit_status = 1;
  }
END:
  NAG_FREE(ab);
  NAG_FREE(b);

  return exit_status;
}

#undef AB_LOWER
#undef AB_UPPER
#undef B