GSoC, Week 6

During week 5, I submitted my pull request. During this past week, I have been working on getting that code to high enough quality to be accepted. It looks like Brian Granger has implemented a change in SymPy’s derivatives in a branch which allows for differentiation of arbitrary things; this includes functions and derivatives, allowing you to take the derivative of an expression with respect to another expression. So in the upcoming week, I’ll be testing how well that can be integrated with physics.mechanics.

This past week, I also started working on the sphinx documentation for the physics.mechanics subsubmodule.  Luke already started a branch for this, so I merged this into my pydy dev branch and got to work. I am currently organizing it in the form: Vector & ReferenceFrame, Kinematics, Masses/Inertias, Forces, and Kane’s Method (and References). This actually follows the order I learned dynamics in my Advanced Dynamics course and also (roughly) the order things were coded in.

So far I filled in the 1st of these, Vector & ReferenceFrame. I first covered all of the math for this, then the code to use it. I did this because the basis vectors are what form other vectors, so you need to have access to them to do any Vector operations. The basis vectors are attributes of ReferenceFrame objects though, which I believe should come after a discussion of Vector (based off of when I learned the concepts).  I also looked through the autolev user’s book; in there they have the example code create reference frames (which automatically creates basis vectors for the user to interact with), and then wait until later for a full discussion of reference frames. I’m not sure which is the better choice for order to discuss things in. Some of the other documentation in SymPy looks more like the autolev manual, with code and math together.  I feel like I might want to switch the order I did Vector & ReferenceFrame in.  Any suggestions here would be nice though.  I think I’ll wait to push the work I’ve done here until I get the chance to organize the commits better, to avoid last week’s issue of changing commit history after pushing; I’ll try and do this on Monday.

I think I’ll also have to learn how to make good figures for this, which might involve learning PSTricks, or something of that nature.  A lot of the information/knowledge that you need to understand what is going on in physics.mechanics needs to be communicated visually.  So far I made some sketches by hand and scanned them, so I know what each image should have and can discuss it appropriately, but the quality is certainly lacking. Some vector graphics here would probably be the best choice.

There’s not that much to report this week due to a day of traveling and a lot of documentation work. I’ve learned that putting a ton of  LaTeX markup in the sphinx documentation can be time consuming. I have the feeling that image creation might be the same way. Fortunately, I have the next 2 weeks to spend on documentation. Hopefully I can keep making progress on my pull request this week too.


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