1. Mathematical Functions

In mathematics, a function is a mapping from a set of inputs to exactly one output.

• It’s pure: no side effects, always gives the same output for the same input.
• Usually written as: f(x) = x + 1
• Inputs are from a domain, and outputs belong to a codomain.

Examples:

• f(x) = x²
• g(x, y) = x + y

In math, functions are definitions, not instructions—no looping, no memory, just relationships.