inline const T standard_deviation()

in Source/Shared/arcana/algorithm.h [291:308]

• 16 lines of code
• 4 McCabe index (conditional complexity)

    inline const T standard_deviation(IteratorT from, IteratorT to, ModifierT&& modifier)
    {
        const auto n = std::distance(from, to);
        if (n <= 1)
        {
            assert(false && "your collection cannot have less than two items");
            return {};
        }

        const auto calculatedMean = mean<T>(from, to, modifier);
        const auto accum = sum<T>(from, to, [&](const typename IteratorT::value_type& currentValue)
                            {
                                T delta = modifier(currentValue) - calculatedMean;
                                return delta * delta;
                            });

        return std::sqrt(accum / (n - 1));
    }