[texhax] FW: Arrow head too large on \overarrowright

[Bob Tennent]

 > > you've omitted a definition of \m at th.

 > That is a standard macro.

Donald: 

  \documentclass{amsbook}
  \makeatletter
  \def\overarrow@#1#2#3{\vbox{%
   \ialign{##\crcr#1{\smaller at than#2}\crcr
   \noalign{\nointerlineskip\kern.12ex}$\m at th\hfil#2#3\hfil$\crcr}}}
  \def\smaller at than#1{\ifx\scriptstyle#1\scriptscriptstyle\else
    \ifx\scriptscriptstyle#1\scriptscriptstyle\else
    \scriptstyle\fi\fi}
  \makeatother
  \begin{document}
  $\overrightarrow{AB}+\overrightarrow{BC}=\overrightarrow{AC}$
  \end{document}

  :

  ! Undefined control sequence.
  <recently read> \m 
                     
  l.11 $\overrightarrow{AB}
                           +\overrightarrow{BC}=\overrightarrow{AC}$

Bob T.