/* nag_lapacklin_dpbsvx (f07hbc) Example Program.
 *
 * Copyright 2024 Numerical Algorithms Group.
 *
 * Mark 30.3, 2024.
 */
#include <nag.h>
#include <stdio.h>

int main(void) {

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

  /* Arrays */
  double *ab = 0, *afb = 0, *b = 0, *berr = 0, *ferr = 0;
  double *s = 0, *x = 0;
  char nag_enum_arg[40];

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

#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_dpbsvx (f07hbc) 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)) ||
      !(afb = NAG_ALLOC((kd + 1) * n, double)) ||
      !(b = NAG_ALLOC(n * nrhs, double)) || !(berr = NAG_ALLOC(nrhs, double)) ||
      !(ferr = NAG_ALLOC(nrhs, double)) || !(s = NAG_ALLOC(n, double)) ||
      !(x = NAG_ALLOC(n * nrhs, double))) {
    printf("Allocation failure\n");
    exit_status = -1;
    goto END;
  }

  pdab = kd + 1;
  pdafb = kd + 1;
#ifdef NAG_COLUMN_MAJOR
  pdb = n;
  pdx = n;
#else
  pdb = nrhs;
  pdx = 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_dpbsvx (f07hbc). */
  fflush(stdout);
  nag_lapacklin_dpbsvx(order, Nag_EquilibrateAndFactor, uplo, n, kd, nrhs, ab,
                       pdab, afb, pdafb, &equed, s, b, pdb, x, pdx, &rcond,
                       ferr, berr, &fail);
  if (fail.code != NE_NOERROR && fail.code != NE_SINGULAR) {
    printf("Error from nag_lapacklin_dpbsvx (f07hbc).\n%s\n", fail.message);
    exit_status = 1;
    goto END;
  }

  /* Print solution using nag_file_print_matrix_real_gen (x04cac). */
  nag_file_print_matrix_real_gen(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n,
                                 nrhs, x, pdx, "Solution(s)", 0, &fail);
  if (fail.code != NE_NOERROR) {
    printf("\nError from nag_file_print_matrix_real_gen (x04cac).\n%s\n",
           fail.message);
    exit_status = 1;
    goto END;
  }

  /* Print error bounds, condition number and the form of equilibration */
  printf("\nBackward errors (machine-dependent)\n");
  for (j = 0; j < nrhs; ++j)
    printf("%11.1e%s", berr[j], j % 7 == 6 ? "\n" : " ");

  printf("\n\nEstimated forward error bounds (machine-dependent)\n");
  for (j = 0; j < nrhs; ++j)
    printf("%11.1e%s", ferr[j], j % 7 == 6 ? "\n" : " ");

  printf("\n\nEstimate of reciprocal condition number\n%11.1e\n\n", rcond);
  if (equed == Nag_NoEquilibration)
    printf("A has not been equilibrated\n");
  else if (equed == Nag_RowAndColumnEquilibration)
    printf("A has been row and column scaled as diag(S)*A*diag(S)\n");
  if (fail.code == NE_SINGULAR) {
    printf("Error from nag_lapacklin_dpbsvx (f07hbc).\n%s\n", fail.message);
    exit_status = 1;
  }
END:
  NAG_FREE(ab);
  NAG_FREE(afb);
  NAG_FREE(b);
  NAG_FREE(berr);
  NAG_FREE(ferr);
  NAG_FREE(s);
  NAG_FREE(x);

  return exit_status;
}

#undef AB_UPPER
#undef AB_LOWER
#undef B