Lab4

I commented out all text I didn't keep. There are also pictures in this folder that aren't being used right now. Should I delete these?
Just a thought with regards to inverting matrices, we may want to mention the fact that inverting a sparse matrices is a VERY BAD IDEA. Jeff gave me this link: http://www.johndcook.com/blog/2010/01/19/dont-invert-that-matrix/