参数中的C++协方差

Cov(X, Y) = Σ[(xi - E(X))(yi - E(Y))] / (n - 1)

#include<iostream>
#include<vector>
#include<numeric>
#include<iterator>

int main() {
    std::vector<double> x = {1, 2, 3, 4, 5};
    std::vector<double> y = {2, 4, 6, 8, 10};

    double mean_x = std::accumulate(x.begin(), x.end(), 0.0) / x.size();
    double mean_y = std::accumulate(y.begin(), y.end(), 0.0) / y.size();

    double cov = 0.0;
    for (size_t i = 0; i < x.size(); ++i) {
        cov += (x[i] - mean_x) * (y[i] - mean_y);
    }
    cov /= (x.size() - 1);

    std::cout << "Covariance: "<< cov<< std::endl;

    return 0;
}