Number
A mathematical object used to count, measure, or label.
- Number systems nest: naturals → integers → rationals → reals → complex.
- ML works almost entirely in the reals (via floats).
- Choosing the right system drives data type and model choice.
When to use: Setting up any data type or interpretation: counts vs. continuous quantities.
Example: Pixel intensity: integer 0-255. Probability: real in [0, 1]. User ID: integer label, not a math quantity.