计算标准差（c++）

#include<iostream>
using namespace std;
int main(){
	cout << "计算 a b c d e 五个数的标准差" << endl;
	double a = 0;
		cout << "请输入a的数值:" << endl;
	cin >> a;
	double b = 0;
		cout << "请输入b的数值：" << endl;
		cin >> b;
	double c = 0;
		cout << "请输入c的数值：" << endl;
	cin >> c;	
	double d = 0;
	cout << "请输入d的数值：" << endl;
	cin >> d;	
	double e = 0;
		cout << "请输入e的数值：" << endl;
	cin >> e;
	double r = (a + b + c + d + e) / 5;
	double t = ((a-r)*(a - r) +(b-r) * (b - r) + (c-r) * (c - r) + (d-r) * (d - r) + (e-r) * (e - r))/5;
	double s = pow(t, 0.5);
			cout << "a b c d e 五个数的标准差是：" << s << endl;
system("pause");
return 0;
}