Maths for ML / Notation

x^{2}

exponent

Arithmetic and relationsBeginner

Say it “x squared”

Multiply x by itself that many times. Careful: a superscript in parentheses x⁽ⁱ⁾ is an index, not a power.

Example

3^{2} = 9

In code

x**2

x**2

Where you’ll see it in ML

Squared error, variance, L2 penalties.

Don’t confuse it with

$x_i,\ x_{ij},\ x^{(i)}$ subscripts & superscript indices xᵢ is the i-th entry of a vector; x_{ij} is row i, column j of a matrix; x⁽ⁱ⁾ (in parentheses) usually means the i-th training example — not a power.

Lessons that use it

← All 94 symbols