计算向量标准差的std::inner_product

#include <iostream>
#include <vector>
#include <numeric>
#include <cmath>

double calculateStandardDeviation(const std::vector<double>& vec) {
    double mean = std::accumulate(vec.begin(), vec.end(), 0.0) / vec.size();
    
    std::vector<double> squaredDifferences(vec.size());
    std::transform(vec.begin(), vec.end(), squaredDifferences.begin(),
                   [mean](double x) { return (x - mean) * (x - mean); });
    
    double meanSquaredDifference = std::accumulate(squaredDifferences.begin(), squaredDifferences.end(), 0.0) / vec.size();
    
    return std::sqrt(meanSquaredDifference);
}

int main() {
    std::vector<double> vec = {1.0, 2.0, 3.0, 4.0, 5.0};
    double standardDeviation = calculateStandardDeviation(vec);
    
    std::cout << "Standard Deviation: " << standardDeviation << std::endl;
    
    return 0;
}