Covariance is--we'll call it--now we have two random variables, so cov... I'll just talk about it in a sample term.

协方差是...我们有两个随机变量,x和y的协方差是,从样本的角度来说

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So if, in fact, we want to describe a wave function, we know that we need to describe it in terms of all three quantum numbers, and also as a function of our three positional factors, which are r, the radius, phi plus the two angles, theta and phi.

实际上，我们想描述波函数，我们知道我们需要,用这三个量子数来描述它，同样，波函数还是,三个位置变量的函数，它们是r半径，还有两个角度theta和。

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