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From: ogawa@orion.arc.nasa.gov (Arthur Ogawa)
Newsgroups: comp.text.tex
Subject: Re: Feynman slash -- question
Message-ID: <1991Mar4.231207.25665@news.arc.nasa.gov>
Date: 4 Mar 91 23:12:07 GMT
References: <1960@ruunsa.fys.ruu.nl> <45048@ut-emx.uucp>
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In article <45048@ut-emx.uucp> myers@ut-emx.uucp (Eric Myers) writes:
|In article <1960@ruunsa.fys.ruu.nl> spit@ruunsa.fys.ruu.nl (Werenfried
|Spit) writes: 
|>
|>I know it has been asked before,but is there
|>someone having a good solution for the so
|>called Feynman slash: a '/' put through a symbol.
|
|To do it right you really should define each symbol with a slash
|through it separately to make it look correct.  In place of all
|that work though here is \slashchar from TeXsis:
|
|
|%  \slashchar puts a slash through a character to represent contraction
|%  with Dirac matrices. Use \not instead for negation of relations, and use
|%  \hbar for hbar.
|
|\def\slashchar#1{\setbox0=\hbox{$#1$}           % set a box for #1 
|   \dimen0=\wd0                                 % and get its size
|   \setbox1=\hbox{/} \dimen1=\wd1               % get size of /
|   \ifdim\dimen0>\dimen1                        % #1 is bigger
|      \rlap{\hbox to \dimen0{\hfil/\hfil}}      % so center / in box
|      #1                                        % and print #1
|   \else                                        % / is bigger
|      \rlap{\hbox to \dimen1{\hfil$#1$\hfil}}   % so center #1
|      /                                         % and print /
|   \fi}                                         %
|

Eric's implementation won't work well within super or supersuperscripts;
a no-fuss implementation is to type, eg,

\not\gamma

This uses the cmsy character "34, the zero-width slash. It was invented 
for precisely this application. It works with Computer Modern math fonts,
but not necessarily other math fonts, so be careful if you've pulled
PostScript fonts into your macro package. It does work with script
and scriptscript typesetting.