covariances

协方差:两个实值随机变量 X、Y 的协方差定义为 Cov(X,Y)=E[(X-μ)(Y-ν)],其中 μ=E(X),ν=E(Y)。

A statistical measure defined as scriptstyle operatorname Cov(X,Y)= operatorname E((X-μ)(Y-ν)) given two real-valued random variables X and Y, with expected values scriptstyle E(X),=,μ and scriptstyle E(Y),=,ν.

在某些情况下,数据类型从较宽类型向较窄类型的转换。

The conversion of data types from wider to narrower in certain situations.