计算数据的平均值、方差和标准差

//计算数据的平均值、方差和标准差

#include <iostream>

#include <math.h>

using namespace std;

class MeanVar

{

private:

int i, n;

double xbar, var, std_dev;

double *x;

public:

MeanVar()

{

xbar = var = 0.0;

}

void mean_var();

~MeanVar()

{

delete[] x;

}

};

void main()

{

MeanVar moments;

moments.mean_var();

}

void MeanVar::mean_var()

{

cout << "\n输入观测次数：";

cin >> n;

x = new double
;

for (i = 0; i < n; i++)

{

cout << "\n输入x[" << i << "] = ";

cin >> x[i];

}

for (i = 0; i < n; i++)

{

xbar += x[i];

}

xbar /= n;

cout << "\n平均值 = " << xbar << endl;

for (i = 0; i < n; i++)

{

var += (x[i] - xbar)*(x[i] - xbar);

}

var /= (n-1);

cout << "\n方差 = " << var << endl;

std_dev = sqrt(var);

cout << "\n标准差是 " << std_dev << endl;

}