Expression
A combination of numbers, variables, and operations - no equals sign.
- Computes a value once variables are filled in.
- Can be simplified without changing what it evaluates to.
- Every ML formula is an expression.
When to use: Anywhere you need to read code as a series of computations.
Example: (1/n)·Σ(y − ŷ)² is an expression. Substitute n, y, ŷ to get a number.