Method std

src/util/shared_array.h:147–150

  double sum() const { return eigenArray().sum(); }
  double mean() const { return empty() ? 0 : sum() / (double)size(); }
  double std() const {
    return empty() ? 0 :
        (eigenArray() - mean()).matrix().norm() / sqrt((double)size());
  }

  // convert to a dense matrix, zero-copy
  shared_ptr<Matrix<V>> matrix(size_t rows = -1, size_t cols = -1);