Suppose I take the variable $X_a$ and square it. To be clear, the _a is part of the variable's name, whereas the ^2 will denote the mathematical operation of squaring.

I could typeset this as

  • $X_a^2$
  • $X_a{}^2$
  • $(X_a)^2$

Is there an accepted convention about which approach is best?

closed as primarily opinion-based by JouleV, Raaja, Stefan Pinnow, Kurt, TeXnician Mar 4 at 11:43

Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise. If this question can be reworded to fit the rules in the help center, please edit the question.

  • 6
    The most normal one is probably the first. Two is uncommon in the fields I work with. Third would probably be best if you are afraid your readers will not understand the first type – daleif Nov 30 '18 at 15:18
  • 1
    I’d also go for either the first or the third choice. The final choice should depend importantly on what exactly X_a denotes. Are there also variables named X_b, X_c, etc? Incidentally, if X_a were an n-tupel, I would write its inner product as {X_a}’X_a, to make sure that the transpose symbol is not placed directly above the letter a. – Mico Nov 30 '18 at 16:17