CeedMath is a library for doing computer graphics math on Mac and iPhone, although it could be ported to other environments easily.
CeedMath is about computation with vectors and matrices, as well as boxes, rays, quaternions, and other CG types. It was designed to be easy to use and understand, and at the same time small and efficient.
CeedMath has simple data structures and operates easily with other formats. It is implemented in C with a form of template that allows a single implementation for both float and double types. That makes it possible to use it as is in Obj-C code. A polymorphic C++ version is also automatically derived.
The library, requirements, steps for including the library in a project, and a code example are available on GitHub (BSD-license).