/* nag_lapacklin_dtrrfs (f07thc) Example Program.
 *
 * Copyright 2024 Numerical Algorithms Group.
 *
 * Mark 30.2, 2024.
 */

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

int main(void) {

  /* Scalars */
  Integer i, j, n, nrhs, berr_len, ferr_len;
  Integer pda, pdb, pdx;
  Integer exit_status = 0;
  Nag_UploType uplo;

  NagError fail;
  Nag_OrderType order;
  /* Arrays */
  char nag_enum_arg[40];
  double *a = 0, *b = 0, *berr = 0, *ferr = 0, *x = 0;

#ifdef NAG_COLUMN_MAJOR
#define A(I, J) a[(J - 1) * pda + I - 1]
#define B(I, J) b[(J - 1) * pdb + I - 1]
#define X(I, J) x[(J - 1) * pdx + I - 1]
  order = Nag_ColMajor;
#else
#define A(I, J) a[(I - 1) * pda + J - 1]
#define B(I, J) b[(I - 1) * pdb + J - 1]
#define X(I, J) x[(I - 1) * pdx + J - 1]
  order = Nag_RowMajor;
#endif

  INIT_FAIL(fail);

  printf("nag_lapacklin_dtrrfs (f07thc) Example Program Results\n\n");

  /* Skip heading in data file */
  scanf("%*[^\n] ");
  scanf("%" NAG_IFMT "%" NAG_IFMT "%*[^\n] ", &n, &nrhs);
  berr_len = nrhs;
  ferr_len = nrhs;
#ifdef NAG_COLUMN_MAJOR
  pda = n;
  pdb = n;
  pdx = n;
#else
  pda = n;
  pdb = nrhs;
  pdx = nrhs;
#endif

  /* Allocate memory */
  if (!(a = NAG_ALLOC(n * n, double)) || !(b = NAG_ALLOC(n * nrhs, double)) ||
      !(berr = NAG_ALLOC(berr_len, double)) ||
      !(ferr = NAG_ALLOC(ferr_len, double)) ||
      !(x = NAG_ALLOC(n * nrhs, double))) {
    printf("Allocation failure\n");
    exit_status = -1;
    goto END;
  }

  /* Read A and B from data file, and copy B to X */
  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);

  if (uplo == Nag_Upper) {
    for (i = 1; i <= n; ++i) {
      for (j = i; j <= n; ++j)
        scanf("%lf", &A(i, j));
    }
    scanf("%*[^\n] ");
  } else {
    for (i = 1; i <= n; ++i) {
      for (j = 1; j <= i; ++j)
        scanf("%lf", &A(i, j));
    }
    scanf("%*[^\n] ");
  }
  for (i = 1; i <= n; ++i) {
    for (j = 1; j <= nrhs; ++j)
      scanf("%lf", &B(i, j));
  }
  scanf("%*[^\n] ");
  for (i = 1; i <= n; ++i) {
    for (j = 1; j <= nrhs; ++j)
      X(i, j) = B(i, j);
  }

  /* Compute solution in the array X */
  /* nag_lapacklin_dtrtrs (f07tec).
   * Solution of real triangular system of linear equations,
   * multiple right-hand sides
   */
  nag_lapacklin_dtrtrs(order, uplo, Nag_NoTrans, Nag_NonUnitDiag, n, nrhs, a,
                       pda, x, pdx, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_lapacklin_dtrtrs (f07tec).\n%s\n", fail.message);
    exit_status = 1;
    goto END;
  }

  /* Compute backward errors and estimated bounds on the */
  /* forward errors */

  /* nag_lapacklin_dtrrfs (f07thc).
   * Error bounds for solution of real triangular system of
   * linear equations, multiple right-hand sides
   */
  nag_lapacklin_dtrrfs(order, uplo, Nag_NoTrans, Nag_NonUnitDiag, n, nrhs, a,
                       pda, b, pdb, x, pdx, ferr, berr, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_lapacklin_dtrrfs (f07thc).\n%s\n", fail.message);
    exit_status = 1;
    goto END;
  }

  /* Print solution */

  printf("\n");
  /* nag_file_print_matrix_real_gen (x04cac).
   * Print real general matrix (easy-to-use)
   */
  fflush(stdout);
  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("Error from nag_file_print_matrix_real_gen (x04cac).\n%s\n",
           fail.message);
    exit_status = 1;
    goto END;
  }
  printf("\nBackward errors (machine-dependent)\n");

  for (j = 1; j <= nrhs; ++j)
    printf("%11.1e%s", berr[j - 1], j % 7 == 0 ? "\n" : " ");
  printf("\nEstimated forward error bounds "
         "(machine-dependent)\n");
  for (j = 1; j <= nrhs; ++j)
    printf("%11.1e%s", ferr[j - 1], j % 7 == 0 ? "\n" : " ");
  printf("\n");
END:
  NAG_FREE(a);
  NAG_FREE(b);
  NAG_FREE(berr);
  NAG_FREE(ferr);
  NAG_FREE(x);

  return exit_status;
}