# Color Inside an Array

I am using the packages amsmath and color.

The following works to color an entire array blue:

\documentclass{article}
\usepackage{amsmath}
\usepackage{color}
\begin{document}

${\color{blue} \left( \begin{array}{c} 1\\ -3 \end{array} \right) }$

\end{document}


If I just want the numbers to be blue, I can move the \color inside the parens:

\documentclass{article}
\usepackage{amsmath}
\usepackage{color}
\begin{document}

$\left( {\color{blue} \begin{array}{c} 1\\ -3 \end{array} } \right)$

\end{document}


That works. However, if I move the \color inside the array, it does not work. The two errors are

Missing } inserted

and

Extra }, or forgotten \$.

\documentclass{article}
\usepackage{amsmath}
\usepackage{color}
\begin{document}

$\left( \begin{array}{c} {\color{blue} 1\\ -3 } \end{array} \right)$

\end{document}


Why does that not work?

• remove grouping { } inside array and you'll see. – touhami Oct 10 '15 at 19:11
• In array environment each column is group (in this case each raw) so you have error 1) \begingroup{ color{blue} 1\endgroup error 2 \begingroup 3}\endgroup – touhami Oct 10 '15 at 19:16
• @touhami, When I remove grouping inside the array, only the 1 gets colored blue, not the -3. What is that supposed to be indicative of? – Daniel S. Oct 10 '15 at 19:17
• each cell is a group, you can not start a group in one cell and end it in another. – David Carlisle Oct 10 '15 at 20:51

\documentclass{article}
$\left( \begin{array}{@{}>{\color{blue}}c@{}} 1\\ -3 \end{array} \right)$