How to use this guide

Each of the 29 chapters follows the same shape:

## N. Topic Name
**Level:** Beginner / Intermediate / Expert
**You'll use this for:** <the 1-line reason a senior engineer needs it>

- The idea (plain language)
- The formula / mechanism, with a table naming every symbol
- Worked example (by hand, with real numbers), directly under the formula
- The theorems behind it, and how AI and networking systems use it
- Code (Python, runnable)
- Real-life engineering ties (SWE / AI / Network / Security)
- Common mistake

Read top to bottom the first time. After that, use it as a reference — jump straight to the chapter you need. Chapters build on each other roughly in order, but each is self-contained enough to read alone.

Tools you need: Python 3 with the small scientific Python stack below. A terminal. Every worked example below can be pasted into a Python REPL.

python3 -m venv venv && source venv/bin/activate
pip install numpy matplotlib scipy sympy scikit-learn pandas
python3