What are some useful functions in a C++ statistics library?

What are some useful functions in a C++ statistics library?

A C++ statistics library typically includes functions for mean, median, mode, variance, and standard deviation.

Can you explain how to calculate the variance using a C++ function?

Sure! Variance can be calculated by taking the average of the squared differences from the mean. Here's a simple function:

double calculateVariance(const std::vector<double>& data) {
    double mean = std::accumulate(data.begin(), data.end(), 0.0) / data.size();
    double variance = 0.0;
    for (double value : data) {
        variance += (value - mean) * (value - mean);
    }
    return variance / data.size();
}

What about calculating the standard deviation?

The standard deviation is simply the square root of the variance. You can modify the previous function to return the standard deviation like this:

#include <cmath>

double calculateStandardDeviation(const std::vector<double>& data) {
    return std::sqrt(calculateVariance(data));
}

Are there any libraries that provide these functions out of the box?

Yes, libraries like Boost and Eigen offer extensive statistical functions, including variance and standard deviation.