C++博客-身上无钱你莫邪-最新评论http://www.cppblog.com/moye/CommentsRSS.aspxmoye's c++ blogzh-cnFri, 27 Feb 2009 04:25:07 GMTFri, 27 Feb 2009 04:25:07 GMTcnblogsre: c++计算标准差http://www.cppblog.com/moye/archive/2009/05/14/69158.html#82996mmThu, 14 May 2009 14:39:00 GMThttp://www.cppblog.com/moye/archive/2009/05/14/69158.html#82996#include <vector>
#include <cmath>

using namespace std;

int main(void)
{
int a[] = {6, 3, 7, 1, 4, 8, 2, 9, 11, 5};
int length = sizeof(a) / sizeof(a[0]); // 获取数组的长度
vector<int> va(a, a + length);

// 求标准差
double sum = 0.0;
for (vector<int>::iterator iter = va.begin(); iter != va.end(); ++iter) // 求和
{
sum += *iter;
}
double avg = sum / va.size(); // 求平均值
sum = 0.0;
for (vector<int>::iterator iter = va.begin(); iter != va.end(); ++iter) // 求和
{
double tmp = *iter - avg;
//sum += pow(tmp, 2.0);
sum += tmp * tmp;
}
double s = sqrt(sum / va.size() );

cout << "标准差为: " << s << endl;

return 0;
}

m 2009-05-14 22:39 发表评论
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