Function standard_deviation

extlibs/catch/include/catch/catch.hpp:7421–7428

    }

    double standard_deviation(std::vector<double>::iterator first, std::vector<double>::iterator last) {
        auto m = Catch::Benchmark::Detail::mean(first, last);
        double variance = std::accumulate(first, last, 0., [m](double a, double b) {
            double diff = b - m;
            return a + diff * diff;
            }) / (last - first);
            return std::sqrt(variance);
    }

}