/* nag_blast_dtpsv (f16plc) Example Program.
 *
 * Copyright 2024 Numerical Algorithms Group.
 *
 * Mark 30.2, 2024.
 */

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

int main(void) {

  /* Scalars */
  double alpha;
  Integer ap_len, exit_status, i, incx, j, n, xlen;

  /* Arrays */
  double *ap = 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 A_UPPER(I, J) ap[J * (J - 1) / 2 + I - 1]
#define A_LOWER(I, J) ap[(2 * n - J) * (J - 1) / 2 + I - 1]
  order = Nag_ColMajor;
#else
#define A_LOWER(I, J) ap[I * (I - 1) / 2 + J - 1]
#define A_UPPER(I, J) ap[(2 * n - I) * (I - 1) / 2 + J - 1]
  order = Nag_RowMajor;
#endif

  exit_status = 0;
  INIT_FAIL(fail);

  printf("nag_blast_dtpsv (f16plc) Example Program Results\n\n");

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

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

  /* 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);

  ap_len = n * (n + 1) / 2;
  xlen = MAX(1, 1 + (n - 1) * ABS(incx));

  if (n > 0) {
    /* Allocate memory */
    if (!(ap = NAG_ALLOC(ap_len, 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 A and vector x */

  if (uplo == Nag_Upper) {
    for (i = 1; i <= n; ++i) {
      if (diag == Nag_NonUnitDiag)
        scanf("%lf", &A_UPPER(i, i));
      for (j = i + 1; j <= n; ++j)
        scanf("%lf", &A_UPPER(i, j));
    }
    scanf("%*[^\n] ");
  } else {
    for (i = 1; i <= n; ++i) {
      for (j = 1; j < i; ++j)
        scanf("%lf", &A_LOWER(i, j));
      if (diag == Nag_NonUnitDiag)
        scanf("%lf", &A_LOWER(i, i));
    }
    scanf("%*[^\n] ");
  }
  for (i = 0; i < xlen; ++i)
    scanf("%lf%*[^\n] ", &x[i]);

  /* nag_blast_dtpsv (f16plc).
   * Solution of real triangular system of linear equations,
   * using packed storage.
   */
  nag_blast_dtpsv(order, uplo, trans, diag, n, alpha, ap, x, incx, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_blast_dtpsv.\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(ap);
  NAG_FREE(x);

  return exit_status;
}