Function common_average

src/program.cpp:867–872

}

static double common_average(const std::vector<double>& v)
{
    std::size_t n = v.size() / 4;
    double total  = std::accumulate(v.begin() + n, v.end() - n, 0.0);
    return total / std::distance(v.begin() + n, v.end() - n);
}

static double mean(const std::vector<double>& v)
{