[Tex/LaTex] How to get rid of “c-cedilla” in math mode

errorsmacros

This code:

\documentclass{scrartcl}
\providecommand{\c}{\mathrm{c}}
\begin{document}
  Complement of $A$: $A^\c$.
\end{document}

Produces the following error:

! Missing { inserted.
<to be read again> 
                   \begingroup 
l.6   Complement of $A$: $A^\c
                              $.
!  ==> Fatal error occurred, no output PDF file produced!

The problem is that the command \c already exists (denotes a "c-cedilla"). However, I would rather like to use \c to denote set complements in math mode.

It seems that for some reason LaTeX cannot switch from text mode to math mode. How can I get rid of "c-cedilla" and get a normal 'c' in math mode?

Best Answer

This redefines it for math mode only, retaining its original use in text mode. EDITED , per egreg's recommendation, to use \DeclareRobustCommand in lieu of \def. The \expandafter in the definition allows the following \fi to be absorbed, so that the text version of \c can operate on the actual argument that follows.

\documentclass{book}
\let\svc\c
\DeclareRobustCommand\c{\ifmmode\mathrm{c}\else\expandafter\svc\fi}
\begin{document}
This is a \c complicated test.

Complement of $A$: $A^\c$.
\end{document}

enter image description here

Related Solutions

[Tex/LaTex] \newcommand gives errors in math mode (with or without arguments)

Here is an alternative to your current situation - using an optional argument to specify the derivative order. This way you don't have to define a macro for "each" derivative:

\deriv[<order>]{<func>}{<var>}

Here's a minimal example:

enter image description here

\documentclass{article}
\newcommand{\deriv}[3][]{% \deriv[<order>]{<func>}{<var>}
  \ensuremath{\frac{\partial^{#1} {#2}}{\partial {#3}^{#1}}}}
\begin{document}
In text mode there is~\deriv{y}{x} and~\deriv[2]{y}{x}. In display mode there is
\[
  \deriv{y}{x}\ \textrm{and}\ \deriv[2]{y}{x}\rlap{.}
\]
\end{document}

The default <order> is empty, implying the first order partial derivative. If you want the default to be 2, modify the definition to read

\newcommand{\deriv}[3][2]{...}

Technically it is possible to use a macro with numbers in them, but the usage is much less intuitive than adding something like an optional argument (as given above). Here's an implementation that now allows you to use \nameuse{deriv2}{y}{x}:

\expandafter\def\csname deriv2\endcsname#1#2{%
  \ensuremath{\frac{\partial^2 {#1}}{\partial {#2}^2}}}
\makeatletter
\newcommand{\nameuse}[1]{\@nameuse{#1}}%
\makeatother

The optional argument beats this hands down.

[Tex/LaTex] error with math mode

You need to be careful to use mathmode correctly; in particular, \mathbb needs to be in mathmode.

You didn't specify what the macro \D does, but it looks as if would you like to use the align environment, as follows

\documentclass{article}

\usepackage{amssymb}
\usepackage{amsmath}
\newcommand{\D}{D}

\begin{document}
 Given a curve $\mathcal{L}$, define two functions of distance transform $\kappa_{+}$ 
 and $\kappa_{-}$ on $\mathbb{R}^{2}$ as 
 \begin{align}
 \kappa_{+}(x) & = d(x,\mathbb{R}^{2}\D), x \in \mathbb{R}^{2} \\
 \kappa_{-}(x) & = d(x,\mathbb{R}^{2}\D), x \in \mathbb{R}^{2}
 \end{align}
\end{document}

Best Answer

Related Solutions

[Tex/LaTex] \newcommand gives errors in math mode (with or without arguments)

[Tex/LaTex] error with math mode

Related Question