Maths for ML / Notation

\frac{df}{dx},\ f'(x)

derivative

CalculusBeginner

Say it “d f d x / f prime of x”

How fast f changes when x changes a tiny bit — the slope.

Example

\frac{d}{dx}x^2 = 2x

In code

(f(x+h) - f(x)) / h  # numerical

y.backward(); x.grad

Where you’ll see it in ML

Every gradient update starts here.

Don’t confuse it with

$\frac{\partial f}{\partial x}$ partial derivative Slope with respect to one input while holding all the others fixed.
$\dot{x}$ Newton's dot (time derivative) Derivative with respect to time.

Lessons that use it

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