Mathematics GRE

I did some coding work for automatically finding out theoretical equations for the Christoffel Symbols for some friends(for helping them with cross-checking their handwritten calculations). I used the symbolic math toolbox and some basic understanding of tensor math in order to do so. Is it relevant enough to be put into my application ? I haven't written a paper or published anything on it though. I just have the code.

I'm not sure how you can really make that sound impressive in an application; it doesn't sound like anything more than an advanced assignment problem to me. Maybe ask a professor what they think. Perhaps you could expand your code and submit it to some open access computer algebra system or something; that would be much more impressive.