# Problem with newly defined command and special chars

I have the following problem. In my document, I defined a new command to save a few chars

\renewcommand{\r}{r_\mathrm{max}}



\end{document}


• Great, that works, thank you. I obviously will not use such short commands anymore. I just didn't know that \r was actually already used. And since it is a complete thesis with over 100 pages, replacing all \r's and checking if it was correctly done would have been a lot of work. So you really saved me some time, thanks – Chris Jun 26 '13 at 20:11

If you look into LaTeX kernel latex.ltx, you will find there the lines

\def \aa {\r a}
\def \AA {\r A}


As you see, ring accent (\r) is used in the definition of \aa and \AA.

It is a bad idea to renew LaTeX commands. You may want to define \myr instead. Just use your text editor to change \r to \myr.

Since the LaTeX kernel latex.ltx has the lines

\def \aa {\r a}
\def \AA {\r A}


you need to do something like

\let\ringaccent\r
\def\aa{\ringaccent a}
\def\aa{\ringaccent a}


before you redefine \r.

I disagree with the opinion that it is quite generally a bad idea to overwrite plain TeX or LaTeX commands. In math typing, you may have excellent reasons to use one-letter macros like \r or \v. Reserving them for rarely or never used accents would be wasteful. Reserving them for just two lines of LaTeX internals would be ridiculous. TeX was meant to give us flexibility; let's use it.