# Is it possible to give colors to big (automatic) parenthesis in math mode?

In the following code I can't make the right parenthesis to have arbitrary colors.

\documentclass{article}
\usepackage{amsmath}
\usepackage{xcolor}
\begin{document}
$$\left(\frac{44}{55}{\color{blue}\right)}$$
\end{document}


As soon as I add color around \right) (or \left() I get an error: ! Missing } inserted.

Is there a work around for this? (I prefer not to touch other parts of the equation).

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– Jubobs Aug 7 '14 at 9:32
Just for you to know why it didn't work: you enclose \right) in the group without \left(. – m0nhawk Aug 7 '14 at 9:35
– Andrea L. Aug 7 '14 at 17:08

It's really easier: \left and \right form a group, so setting the color immediately before \right will do.

\documentclass{article}
\usepackage{amsmath}
\usepackage{xcolor}
\begin{document}
$$\left(\frac{44}{55}\color{red}\right)+2$$
\end{document}


For coloring also the left delimiter, you can save the color before changing it:

\documentclass{article}
\usepackage{amsmath}
\usepackage{xcolor}
\begin{document}
$$\begingroup \colorlet{savedleftcolor}{.} \color{blue}\left(\color{savedleftcolor} \frac{44}{55}\color{red}\right) \endgroup +2$$
\end{document}


A generalized version:

\documentclass{article}
\usepackage{amsmath}
\usepackage{xcolor}

\newcommand{\cleft}[2][.]{%
\begingroup\colorlet{savedleftcolor}{.}%
\color{#1}\left#2\color{savedleftcolor}%
}
\newcommand{\cright}[2][.]{%
\color{#1}\right#2\endgroup
}

\begin{document}
$$\cleft[blue](\frac{44}{55}\cright[red]) + \cleft[red](\frac{44}{55}\cright)$$
\end{document}


Note that \cleft{[} is needed for having the bracket, if no color is specified, or \cleft\lbrack.

Don't try closing \cleft with \right or \left with \cright.

-

Ugly, but works.

\documentclass{article}
\usepackage{amsmath}
\usepackage{xcolor}
\begin{document}
$$\left(\frac{44}{55}\right.{\color{blue}\left.\mkern-7mu\vphantom{\frac{44}{55}}\right)}$$
\end{document}


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Could you maybe explain how you arrived at the \mkern-7mu spacing adjustment? Mainly by "occular regression", or by a somewhat more explicit method? – Mico Aug 7 '14 at 5:13
@Mico eye balling! ;) – Harish Kumar Aug 7 '14 at 5:14

How to do things so complicatedly when there is a simple alternative?

\documentclass{article}
\usepackage{amsmath}
\usepackage{xcolor}
\begin{document}
$$\left(\frac{44}{55}\color{blue}\right)\color{black}$$
\end{document}

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Shouldn't the last just be \normalcolor? – daleif Aug 7 '14 at 6:26
May be Yes. I'am not specialist of (x)color packages and any others LaTeX packages:) – wipet Aug 7 '14 at 6:32
There should be way to remember the colour before it gets changed, then the code could be modified to behave exactly as if the colour command was grouped. And +1 for a genuine idea! :) – yo' Aug 7 '14 at 6:42
Yes. \colorlet{outcolor}{.} to remember current color and \color{outcolor} to restore it. See for example my answer tex.stackexchange.com/questions/46701/… This is more complicated case because the kerning problem have to be solved there. This problem isn't here during typesetting only parenthesis. – wipet Aug 7 '14 at 7:50
Resetting \color{black} is not needed. – egreg Aug 7 '14 at 9:17