# [Tex/LaTex] How to reset \renewcommand\l{\lambda} locally

groupingmacros


#### Best Answer

You cannot reset a \renewcommand. But there are several options.

The cleanest would be to write ł instead of \l directly. This merely requires saving the document as UTF-8 and either using a modern LaTeX processor (LuaTeX or XeLaTeX) or to include the inputenc package with the utf8 option (\usepackage[utf8]{inputenc}).

Alternatively, you can define a new command to include \l immediately before it’s redefined:

\let\lw\l
\renewcommand\l{{\lambda}}


… and then just use \lw in place of \l to typeset ł.

Or you could change the redefinition of \l so that it only includes the λ in math mode, and includes ł in text mode. But I wouldn’t do that – it’s very unintuitive and hard to understand as a reader of the source code. Still, here it is:

\let\oldl\l
\renewcommand\l{\relax\iffmode\lambda\else\oldl\fi}

% … usage:

Here’s a z\l oty for your effort. $\l = 1\ \mL$


… which will render as:

Here’s a złoty for your effort. λ = 1 µL