# Why does \dot over \vec over {\bf E} gives a tilde?

When using AMSmath and trying to put a \dot over a \vec of a bold symbol it works, but subsequent instances have a tilde instead of a vector over the bold symbol, and strangely my partial wrt become bold. If I don't use AMSmath, this works. I have tried many variants with extra brackets or interchanged orders, but nothing seems to fix this bug. Here is a tex snippet that reproduces the problem on the second row, the third row when preceding {\vec E} with \bf produces only tildes instead of vectors, but the \dot make the D not be bold.

Any ideas what I am missing?

\documentclass [12pt] {article}
\usepackage{amsmath,amssymb}

%\let\vec\relax
%\DeclareMathAccent{\vec}{\mathord}{letters}{"7E}
\newcommand{\pdt}[1]{\frac{\partial^{#1}}{\partial t^{#1}}}
\begin{document}

\LARGE
$\vec E \cdot \dot{{\vec D}} = \vec E \cdot \pdt{} (\epsilon \vec E )$

$\vec {\bf E} \cdot \dot {\vec {\bf D}} = \vec {\bf E} \cdot \pdt{} (\epsilon \vec {\bf E} )$

${\bf {\vec E}} \cdot \dot{ {\bf {\vec D}}} = {\bf {\vec E}} \cdot \pdt{} (\epsilon {\bf {\vec E}} )$
\end{document}

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\dot{{\vec {\mathbf D}}} did not work for you? – Harish Kumar Aug 31 '12 at 0:07
the misrendering of \vec with \mathbf is a known bug, and it is on the list to be addressed when amsmath is next overhauled. sadly, that overhaul has not yet been definitively scheduled. – barbara beeton Aug 31 '12 at 12:12

The following should work:

\documentclass [12pt] {article}
\usepackage{amsmath,amssymb}

%\let\vec\relax
%\DeclareMathAccent{\vec}{\mathord}{letters}{"7E}
\newcommand{\pdt}[1]{\frac{\partial^{#1}}{\partial t^{#1}}}
\begin{document}

\LARGE
$\vec {E} \cdot \dot{{\vec {D}}} = \vec {E} \cdot \pdt{} (\epsilon \vec {E} )$

$\vec {\mathbf {E}} \cdot \dot {\vec {\mathbf {D}}} = \vec {\mathbf {E}} \cdot \pdt{} (\epsilon \vec {\mathbf {E}} )$

${\vec {\mathbf {E}}} \cdot \dot{{\vec {\mathbf {D}}}} = {\vec {\mathbf {E}}} \cdot \pdt{} (\epsilon {\vec {\mathbf {E}}} )$
\end{document}


PS: Since you are in math mode, it is better to use \mathbf instead of \bf.

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