gistfile1.txt

#include <iostream>
#include <vector>
#include <random>
#include <chrono>

template <typename T>
static void init(std::vector<T>& v)
{   
    std::mt19937 mt(0);
    for(auto& it : v) {
        it = static_cast<T>(mt());
    }
}

template <typename T>
static double axpy(std::vector<T>& r)
{   
    const auto num = r.size();
    constexpr size_t loop_count = 100;

    double ret = 0.0;

    std::vector<T> A(num);
    std::vector<T> x(num);
    std::vector<T> b(num);

    init<T>(A);
    init<T>(x);
    init<T>(b);

    for(auto l = decltype(loop_count)(0); l < loop_count; ++l) {
        auto start = std::chrono::system_clock::now();
        for(auto i = decltype(num)(0); i < num; ++i) {
            r[i] = A[i] * x[i] + b[i];
        }
        auto end = std::chrono::system_clock::now();
        ret += std::chrono::duration_cast<std::chrono::nanoseconds>(end - start).count();
    }

//    ret /= static_cast<double>(loop_count);
    return ret;
}

int main()
{   
    constexpr size_t num = 4096;
    std::vector<float> vf(num);
    std::vector<double> vd(num);

    auto float_time = axpy<float>(vf);
    auto double_time = axpy<double>(vd);

    for(size_t i = 0; i < 10; ++i) {
        std::cout << vf[i] << " " << vd[i] << std::endl;
    }

    std::cout << "float time " << float_time << " nsec" << std::endl;
    std::cout << "double time " << double_time << " nsec " << std::endl;

    return 0;
}