MathMod is mathematical software for visualizing and animating parametric and implicit surfaces. It is an extension/rewrite of the K3DSurf project. It supports 3D/4D plotting and animation, a scripting language, a JSON file format with a large set of scripted examples, and an OBJ output file of the 3D mesh.
Bitcoin is a peer-to-peer electronic cash system that is completely decentralized, without the need for a central server or trusted parties. Users hold the crypto keys to their own money and transact directly with each other, with the help of a P2P network to check for double-spending.