计算 R 中的平方偏差总和 [英] Calculating sum of squared deviations in R

问题描述

如何计算向量的平方偏差(与平均值)之和?

How can I calculate the sum of squared deviations(from the mean) of a vector?

我尝试使用命令

sum(x-mean(x))^2

sum(x-mean(x))^2

但不幸的是，这返回的是 -1.998401e-15，这不可能是正确的.是否有一个微妙的运算符，比如括号，我可能在这里遗漏了?

but unfortunately what this returns is -1.998401e-15 which cannot be right. Is there a subtle operator, like a parenthesis, that I am missing here perhaps?

谢谢.

推荐答案

这很可能是正确的.-2.0 的 10^15 次方意味着它基本上为零.但正如贾斯汀刚刚在评论中指出的那样，你有

It may well be correct. -2.0 to the power of 10^15 means it is essentially zero. But as Justin just noted in the comment, you have

    (sum (x - mean(x) )^2

你可能的意思是:

    sum( (x - mean(x) )^2 )

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