I am currently writing the scriptum of our theoretical physics lecture. I always have trouble with the notation.

Our professor uses lower indices like m_i for the i-th mass, upper indices like \vec{x}^i to describe the i-th component of x but also \vec{x}^2=\vec{x}\cdot \vec{x}.

Is there a way to clearly distinguish these two cases?

  • You can use x^i instead of \vec{x}^i for the vector component
    – User
    Dec 27 '15 at 18:23
  • 1
    (Upper) indices are typically distinguished from powers by using brackets. That is, x^{(2)} for "the second component of x" compared to x^2 for x squared.
    – Werner
    Dec 27 '15 at 19:11
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    No, there isn't. The notation with upper indices is inherently ambiguous when powers are also used.
    – egreg
    Dec 27 '15 at 19:12
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    @ChristianHupfer However, you can't, in general, take powers of these beasts. I'm sure we've discussed this thing before and came to the conclusion that this has little to do with LaTeX. It's a problem of mathematicians and their notation.
    – yo'
    Dec 27 '15 at 21:01
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    @Werner: I also use parentheses to distinguish upper indices, but to save time (as I take notes in LaTeX), I've added \catcode\"=13` and \newcommand*{"}[1]{^{(#1)}} to my preamble to make this simpler: now, x"2 gives me x^{(2)}. This is also clearly distinct from x_2 and x^2 in my code. Dec 27 '15 at 21:48