# History¶

Dale Peterson started graduate school at UC Davis in Fall of 2006 and met Jason Moore in the [[http://biosport.ucdavis.edu/|Sports Biomechanics Lab]]. They shared a passion for bicycles, dynamics and control and had both taken the multibody system dynamics course at UC Davis (MAE 223, taught by Dr. Mont Hubbard and Dr. Fedelis Eke). This course teaches Kane’s method for deriving equations of motion, and at that time they also taught Autolev (now defunct) in the course. Autolev is very powerful at symbolic dynamics but lacks important functionality and they both found themselves wanting a richer set of tools for studying bicycles, rolling discs, rattlebacks, and other systems that are well described by classical mechanics. They dreamed of creating an open source tool that was more extensible and nicer to use, but at the time neither of them had the programming skills to make the dream a reality.

In Spring of 2007, Dale took Dr. Jim Crutchfield’s graduate physics course in nonlinear dynamics and chaos, in which all homework was required to be done using Python. This was a tall order for a single class! This was Dale’s favorite course in graduate school and his first introduction to chaos and to Python (and some of the chaos of Python). About a year and a half later (December 2008), Dale was tinkering with Python and trying to replicate some of the kinematic functionality that made Autolev so convenient to use. He got some basic classes created and contacted Ondřej Čertík <http://ondrejcertik.com/>, the creator of the SymPy project to see if he was interested in helping him get started. He made a trip up to his apartment one weekend in January of 2009, and before he knew it, he had a good chunk of the functionality he was looking for. Which was really exciting! Ondřej encouraged Dale to apply to a Google Summer of Code, so he did, and he spent the summer of 2009 working on a GSoC project that was a separate project from SymPy. This was a big learning experience, and one of the things that was learned by the end of the summer was that the software should have been part of the SymPy project, rather than its own standalone project. This led to Gilbert Gede (another UC Davis graduate student) taking on a second GSoC project in which he ported the original PyDy code into SymPy as a sub-package sympy.physics.mechanics. This is what is currently is in the SymPy repository. The software was introduced to the UC Davis multibody dynamics course at the beginning of 2012, to replace the aging Autolev. A third GoSC grant allowed Angadh Nanjangud to add Lagrangian dynamics and many other features to the code base during the summer of 2012.