Code conveying the basic concepts.
Top Down Operator Precedence / Pratt Parsing
Article on Top Down Operator Precedence (aka Pratt Parsing), a parsing technique that does not rely on a grammar. Example implementation in JS.
Faster Math Functions by Robin Green
Describes a range of techniques for approximating/optimizing elementary math functions.
Code for Concentric Map
Concentric mapping is a commonly used method for mapping points on a unit square to a unit disc. These are some code samples.
Sean Barrett's Imgui Example Implementation
Good example code for a basic imgui