Maths for ML / Notation

x \mapsto x^2

maps to

FunctionsIntermediate

Say it “x goes to x squared”

Describes what a function does to a single input, like a lambda.

Example

x \mapsto \max(0, x)

That's ReLU.

In code

lambda x: max(0, x)

Where you’ll see it in ML

Defining activations and transforms inline.

Don’t confuse it with

$f: \mathbb{R}^{n} \to \mathbb{R}$ function arrow (type) Says what kind of input a function takes and what kind of output it gives — its type signature.

Lessons that use it

Functions and arrows: f: ℝⁿ → ℝ, ↦ and f ∘ g

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