如何利用C++进行高效的数值计算和科学计算？

#include <iostream>
#include <cmath>

int main() {
    double angle = 30; // 角度
    double radians = angle * M_PI / 180.0; // 角度转弧度
    double sine = std::sin(radians); // 正弦值
    std::cout << "sin(" << angle << ") = " << sine << std::endl;
    
    return 0;
}

#include <iostream>
#include <mkl.h>

int main() {
    const int N = 1000;
    float x[N], y[N], z[N]; // 输入和输出数组
    // 初始化输入数组
    for (int i = 0; i < N; ++i) {
        x[i] = i;
        y[i] = i + 1;
    }
    // 进行矢量化计算
    cblas_saxpy(N, 2.0, x, 1, y, 1, z, 1);
    // 输出结果
    for (int i = 0; i < N; ++i) {
        std::cout << z[i] << " ";
    }
    std::cout << std::endl;
    
    return 0;
}

#include <iostream>
#include <omp.h>

int main() {
    const int N = 1000;
    int result = 0;
    // 并行计算求和
    #pragma omp parallel for reduction(+:result)
    for (int i = 0; i < N; ++i) {
        result += i;
    }
    std::cout << "Sum: " << result << std::endl;
    
    return 0;
}