Fibonacci Hashing: The Optimization that the World Forgot (or: a Better Alternative to Integer Modulo)
Download a PDF, print it out, instant graph paper.
David MacKay has put the textbook he wrote online for everyone to download in a variety of formats. If you find it useful, consider buying a copy.
The full text of _The Handbook of Applied Cryptography_, one of the best textbooks available in the field. The original authors have gotten permission from the publisher to put the text online as sets of PostScript and .pdf files for anyone to download and share.
Convert any number into different numerical bases, such as binary, trinary, octal, and base-20.
A website about randomness, (pseudo-)random number generators, and cryptographic entropy. Contains discussions of these topics as well as some online RNGs to play with.
The subtle wit of Isaac Asimov.
A publisher reprinting rare, forgotten, and unusual texts. Download them as .pdfs or purchase them online. Many categories are represented, from epic sagas to classical fiction, drama to architecture, history to technology.
A free, open source mathematical processing system written in Python.
A graphical application that makes it easier to generate and render in high resolution 3d fractals. Includes many of the classic fractal systems (like Mandelbrot, the Julia set, the Menger sponge, and IFS). All of the supported fractal systems can be hybridized and combined with one another. 64-bit safe. Makes full use of multiple CPUs for rendering. Also supports common graphical functions, like fog rendering, geometric primitives, ambient occlusion, reflection, keyframing, and more.
bulbs visualized-mathematics fractals 3d graphics open-source software
Exponential moving average. Used to smooth spikes out in a stream of numerical data.
From here you can purchase a DIY kit for a circuit that implements the German Enigma cypher from World War II. Fun for cypherpunks, electronics mavens, and geeks!
Just short of a dozen nifty tricks for mental arithmetic.
A python module for parsing mathematical expressions. Figures out the equation you specify (which can be in a spoken language) and solves them.