/* nag_blast_dspr2 (f16psc) Example Program.
 *
 * Copyright 2024 Numerical Algorithms Group.
 *
 * Mark 30.2, 2024.
 */

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

int main(void) {

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

  /* Arrays */
  double *ap = 0, *x = 0, *y = 0;
  char nag_enum_arg[40];

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

#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_dspr2 (f16psc) Example Program Results\n\n");

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

  /* Read the problem dimension */
  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 scalar parameters */
  scanf("%lf%lf%*[^\n] ", &alpha, &beta);
  /* Read increment parameter */
  scanf("%" NAG_IFMT "%" NAG_IFMT "%*[^\n] ", &incx, &incy);

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

  if (n > 0) {
    /* Allocate memory */
    if (!(ap = NAG_ALLOC(ap_len, double)) || !(x = NAG_ALLOC(xlen, double)) ||
        !(y = NAG_ALLOC(ylen, 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) {
      for (j = i; 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));
      scanf("%*[^\n] ");
    }
  }
  for (i = 0; i < xlen; ++i)
    scanf("%lf%*[^\n] ", &x[i]);
  for (i = 0; i < ylen; ++i)
    scanf("%lf%*[^\n] ", &y[i]);

  /* nag_blast_dspr2 (f16psc).
   * Rank two update of real symmetric matrix,
   * packed storage.
   */
  nag_blast_dspr2(order, uplo, n, alpha, x, incx, y, incy, beta, ap, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_blast_dspr2.\n%s\n", fail.message);
    exit_status = 1;
    goto END;
  }

  /* Print updated matrix A */
  /* nag_file_print_matrix_real_packed (x04ccc).
   * Print real packed triangular matrix (easy-to-use)
   */
  fflush(stdout);
  nag_file_print_matrix_real_packed(order, uplo, Nag_NonUnitDiag, n, ap,
                                    "Updated Matrix A", 0, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_file_print_matrix_real_packed (x04ccc).\n%s\n",
           fail.message);
    exit_status = 1;
    goto END;
  }

END:
  NAG_FREE(ap);
  NAG_FREE(x);
  NAG_FREE(y);

  return exit_status;
}