# My prime symbol is not superscript

I'm learning math mode and having an issue here with the prime symbol.

$y\in[0,1]^{d\prime}$


In this inline math formula, the prime symbol is supposed to be superscript, but it shows up at the regular text level and size.

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If you provide a fuller example showing which files and packages you're loading, we could help you better – A.Ellett Feb 3 '13 at 0:51
Informative (and a little bit related): What is the advantage of using $f^\prime$ instead of $f'$? – Qrrbrbirlbel Feb 3 '13 at 1:01

## 2 Answers

It is not clear what you want the output to be

$y\in[0,1]^{d\prime}$


the \prime is in the superscript along with d. If you want the prime to be on d then just use

$y\in[0,1]^{d'}$


which is equivalent to

$y\in[0,1]^{d^{\prime}}$

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Thank you. I needed the extra explanation as well as the answer. I'm not up to speed on this language. – Nathan Feb 3 '13 at 0:54
+1 for noting apostrophe (') is, in math mode, the same as ^{\prime} – Alex Nelson Feb 3 '13 at 16:11
@AlexNelson, I think that that's only approximately true. Namely, $$d'$$ is the same (I guess) as $$d^\prime$$, but $$d''$$ is not the same as $$d^\prime^\prime$$. (I think ' does some \ifnextchar monkeying precisely to handle this.) – L Spice Jun 17 '15 at 20:01
@LSpice \futurelet rather than \@ifnextchar but yes. – David Carlisle Jun 17 '15 at 20:05

\prime is by default on the same level as normal text. (Just as \circ - used as symbol for degrees for example.) Instead you need to specify that \prime is a superscript:

$y\in[0,1]^{d^\prime}$


EDIT: This might be marginal to the question, but I think it's a useful addition. The ' is a shorthand for ^\prime. Thus, if you type in LaTeX:

$y\in[0,1]^{d^{\circ'}}$


the output will be:

As you can see, LaTeX interprets it as a double superscript. Now suppose you don't want that, but instead something like:

If you try to do it by typing: $y\in[0,1]^{d^{\circ}'}$, you'll summon up an error:

! Double superscript.
<recently read> ^
l.4 $y\in[0,1]^{d^{\circ}'  To avoid this, \prime comes handy. Just do: $y\in[0,1]^{d^{\circ\prime}}\$ and everything will be fine. :)

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Duplicated from tex.stackexchange.com/questions/96558/…: I think that "The ' is a shorthand for ^\prime." is only approximately true. Namely, $$d'$$ is the same (I guess) as $$d^\prime$$, but $$d''$$ is not the same as $$d^\prime^\prime$$. (I think ' does some \ifnextchar monkeying precisely to handle this.) – L Spice Jun 17 '15 at 20:04