James K Beard’s Papers page links include recent work on Costas arrays, including exhaustive searches over orders 24, 25, and 26, two new generators, and enumeration of Costas arrays to order 200, including papers in PDF format.
Solomon W. Golomb's Home Page Publisher of many landmark papers on Costas Arrays and coding theory has a home page on the USC server.
Mac Tech Challenge One of the Costas Array nodes of data.
PDF Short Article on an exhaustive generator for Costas Arrays, good for N up to about 23, with Matlab-like code.
Quaternions – A 2.5 MB PDF file from this site that shows how to use quaternions to model rotation of rigid bodies, including dynamic six degrees-of-freedom modeling.
Quaternions CMU Old but good link with code snippets in MATLAB and C
Cayley algebras Hamilton and Cayley did quaternions and such, too – a truly excellent tutorial on the sequence of algebras from real to complex to quaternions to octernions; these are the four Cayley algebras
CLICAL Freeware for Quaternions – “A calculator type computer program for vectors, complex numbers, quaternions, bivectors, spinors, and multivectors in Clifford algebras”
Using Quaternions Berkeley CS 184 – includes a brief tutorial on quaternions and Euler angles
Robotics U of Utah CS 6310 & ME 6220 – uses quaternions in robotic motion software Costas Arrays