mean.hh

#ifndef VTESTBED_BASE_MEAN_HH
#define VTESTBED_BASE_MEAN_HH

#include <ostream>

#include <vtestbed/base/blitz.hh>

namespace vtb {

    namespace base {

        template <class T>
        class Mean {

        public:
            typedef T value_type;
            typedef T& reference;
            typedef const T& const_reference;
            typedef int int_type;

        private:
            T _sum{0};
            int _count{0};

        public:

            inline int_type
            count() const noexcept {
                return this->_count;
            }

            inline value_type
            mean() const noexcept {
                return this->_sum;
            }

            inline void
            update(T x) {
                auto& sum = this->_sum;
                auto& n = this->_count;
                ++n;
                sum += (x - sum) / n;
            }

            inline void
            clear() {
                this->_sum = 0, this->_count = 0;
            }

            inline friend std::ostream&
            operator<<(std::ostream& out, const Mean& rhs) {
                return out << rhs.mean();
            }

        };

    }

}

#endif // vim:filetype=cpp