I am a Chemistry student but we have done some tensors in a course unit. Could anyone explain when a comma or a plus sign is added between terms?
If for example you have the tensor ai you do a1, a2, a3 etc but if you have AijBjl you do when Ai1B1l + Ai2B2l + Ai3B3l and then you expand when I = 1 and l = 1, when I=2 l=1, I=3 l = 1 etc