the two dots above a letter represents two derivative of varible t.

My method:


However,the latex says in the math environment ,I must use the \mathaccent. So I replace \" by \mathaccent, but it shows the warning information: Missing number, treated as zero

I am a starter, I want to know how to revise it? Can someone help me? Thanks sincerely!!

  • 23
    Welcome to TeX.SE. Use $\dot x$ for the first derivative, \ddot x for the second, \dddot x for the third, \ddddot x for the fourth. Jan 8, 2014 at 3:03
  • @Peter Grill,Thaks for your warm welcome and solution.I am a college student.I like Latex very much.
    – mma
    Jan 8, 2014 at 3:08
  • @ Peter Grill,Dear Peter Grill,BTW,how to write the "^" above a letter.\^{u} cannot achieve that effect in the math enviroment.
    – mma
    Jan 8, 2014 at 3:27
  • 4
    – user11232
    Jan 8, 2014 at 3:45
  • I would like to extend this question and ask how one would do the same thing only under the letter or a word
    – tmwitten
    Jul 27, 2015 at 5:00

1 Answer 1


The sequence


will be used when you want to write 'ö' in text, such as 'Schrödinger'. While in the math mode, as Peter Grill mentioned


and so on, should do the trick.


For more than two dots, e.g. \dddot{o}, you need the package amsmath, which allows you a maximum of 4 dots \ddddot{o} (not strikingly beautiful fourth time derivative)

For higher dot derivatives take a look at this post

  • 1
    what package do you need in order to use \"? it does not seem to work by default.
    – elkshadow5
    Dec 12, 2021 at 0:03
  • It should work in the text mode without any additional packages. I checked with only \documentclass{article}\begin{document} Thr\"{o}ugh \end{document}
    – Cain
    Dec 13, 2021 at 11:37
  • How did you type \" ? When I try typing \", it does not work, but when I copy/paste your code, it does.
    – Allure
    Feb 28 at 9:00
  • 1
    It's simply a backslash and a double quotation mark.
    – Cain
    Mar 1 at 9:20

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