C++計算均值方差

C++計算均值方差

void getMeanStd0(const vector<int>& vec, int& mean, double& stdd)
{
	assert(!vec.empty());
	
	mean = 0;
	stdd = 0;

	for (int i = 0; i < vec.size(); ++i)
	{
		mean += vec[i];
	}
	mean /= vec.size();

	for (int i = 0; i < vec.size(); ++i)
	{
		stdd += (vec[i] - mean)*(vec[i] - mean);
	}
	stdd /= (vec.size() - 1);
	stdd = sqrt(stdd);
	
}