Tensors This file covers the math behind a lot of Special and General Relativity. They are somewhat old fashioned in that they use the terminology of covariant and contravariant vectors, whereas within basically the last 50 years, one speaks of one-forms and such. But this way made more sense to me, especially when I was learning it the first time in the context of Jackson's Electrodynamics book. Somehow I made it through an entire course in General Relativity w/o ever really learning the one-forms stuff. Note, Einstein summation notation is heavily, and often implicitly, used.