3

I'm trying to write a dot over a subscript - like

    f_{\dot{x}}

My problem is that this comes out looking all wrong. The dot is inside the x, it's just messy. Does anyone know of a way to do this?

P.S I'm doing this because I want to write the euler-lagrange equations in the more compact form

    f_{x}=\dot{f_{\dot{x}}}

so I need a method that will accompany another dot on top of the one in the subscript. Any help would be appreciated.

Edit: Mico answered this below to all who have the same issue! Thanks Mico!

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  • 2
    You can do f^{}_{\dot{x}}, with a dummy superscript. It's unclear what you want to achieve with f_{x}=\dot{f_{\dot{x}}}: can you show an approximate representation or point to some image?
    – egreg
    May 5, 2017 at 21:20
  • Do you load the amsmath package? Please confirm.
    – Mico
    May 5, 2017 at 21:30
  • Thank you all! Mico answered with exactly what I needed below. May 5, 2017 at 21:39

2 Answers 2

4

If you change from \dot{f_{\dot{x}}} to \dot{f}_{\dot{x}}, both dots will be placed correctly.

enter image description here

\documentclass{article}
\begin{document}
$f_{x}=\dot{f}_{\dot{x}}$
\end{document}

Addendum: A second MWE, which shows the OP's formula, the improvement suggested above, and a possible further improvement on.

enter image description here

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{tabular}{ccc}
bad & good & best(?) \\[1ex]
$\dot{f_{\dot{x}}}$ & $\dot{f}_{\dot{x}}$ & $\dot{f}^{}_{\!\dot{x}}$ 
\end{tabular}
\end{document}
3
  • 1
    Damn you've beaten me by a split second! :)
    – Moriambar
    May 5, 2017 at 21:18
  • 1
    very good for your work +1.
    – Sebastiano
    May 5, 2017 at 21:31
  • Thank you! Exactly what I was looking for. Much obliged to all who commented! May 5, 2017 at 21:38
1

You could do something clunky like this:

\documentclass{article}
\usepackage{amsmath}
\newcommand{\mydot}[1]{\raisebox{-0.5ex}{\scriptsize$\dot{#1}$}}

\begin{document}
\[
f_{\dot x}  \quad f_{\mydot{x}}
\]
\end{document}

enter image description here

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