>using and manipulating tensors [without summing over repeated indices] is extremely painful It's a good notation, but writing a few sigmas in front of every e

>using and manipulating tensors [without summing over repeated indices] is extremely painful It's a good notation, but writing a few sigmas in front of every equation is at worst a constant-factor overhead. I know of a text that does it that way in a (misguided?) attempt to be more approachable to nonspecialists.