Maths for ML / Notation

\bar{x}

bar

FunctionsBeginner

Say it “x bar”

Usually the mean (average) of x. Occasionally a complex conjugate.

Example

\bar{x} = \tfrac{1}{n}\sum_i x_i

In code

x.mean()

x.mean()

Where you’ll see it in ML

Batch statistics and normalization.

Don’t confuse it with

$\hat{y}$ hat An estimate or prediction of the un-hatted quantity.
$\mathbb{E}_{x\sim p}[f(x)]$ expectation The average value you'd get if you sampled many times — weighted by probability.
$\mu$ mu (mean) Conventionally the mean of a distribution.

Lessons that use it

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