lab3

inline double norm_of_vector(const vector<double>& lhs)
{

	double result = 0;

	for (auto& vector_element : lhs)
	{
		result += vector_element * vector_element;
	}

	return sqrt(result);

}

inline double cos_phi_between_vectors(const vector<double> &lhs, const vector<double> &rhs)
{
	if (lhs.size() != rhs.size())
		return -1;

	double result = 0;
	const size_t n = lhs.size();

	for (size_t i = 0; i < n; i++)
		result += lhs[i] * rhs[i];

	return
		result / (norm_of_vector(lhs) * norm_of_vector(rhs));

}