- #1

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## Main Question or Discussion Point

Ok, so here's my problem. I just graduated with a mathematics degree and am going full force into a physics graduate program. I'm taking a course called mathematical methods for physicists, in which the first subject is tensors. Everyone else seems to be comfortable with the material, but me, I'm totally lost. I had a couple linear algebra courses in my undergrad, but it was nothing like this.

First, there's the idea of how to use the superscript and subscript in a transformation/vector. These "index gymnastics" are quite mindboggling to me.

For example, in our notes, the transformed basic vectors [itex]\hat{e'}_{i}=\sum_{j=1}^{N}{e}_{j}A_{j}^{i}[/itex] with A_{j}^{i} being the transformation matrix. The placement of the j's and i's baffle me, and I feel as if I don't get this figured out, I'll be completely lost from here on out (Right now one of our homework problems involves creating these transformation matrices to an oblique system).

See this link for the lecture material (you'll find slides 1-5 describe what I'm having trouble with).

First, there's the idea of how to use the superscript and subscript in a transformation/vector. These "index gymnastics" are quite mindboggling to me.

For example, in our notes, the transformed basic vectors [itex]\hat{e'}_{i}=\sum_{j=1}^{N}{e}_{j}A_{j}^{i}[/itex] with A_{j}^{i} being the transformation matrix. The placement of the j's and i's baffle me, and I feel as if I don't get this figured out, I'll be completely lost from here on out (Right now one of our homework problems involves creating these transformation matrices to an oblique system).

See this link for the lecture material (you'll find slides 1-5 describe what I'm having trouble with).