7

I have this code:

\documentclass[a4paper,11pt]{article}

\usepackage{amsmath}

\begin{document}

$
A = \begin{bmatrix}
a & b & c & d \\
a & b & c & d \\
a & b & c & d \\
a & b & c & d \\
\end{bmatrix}
$

\end{document}

What I want to do is change the color of the first and third column to red.

enter image description here

Thanasis1101
  • 235

3 Answers3

5

If you want to automate this process for an entire column, then you need to have access to the column specification. This is not possible via amsmath's *matrix environments. Instead, use array and insert \color{red} in front of every entry using the >{<prefix>} specification:

enter image description here

\documentclass{article}

\usepackage{amsmath,array,xcolor}

\begin{document}

$
  A = \begin{bmatrix}
    a & b & c & d \\
    a & b & c & d \\
    a & b & c & d \\
    a & b & c & d
  \end{bmatrix} \qquad
  \left[\begin{array}{@{} >{\color{red}}c c >{\color{red}}c c @{}}
    a & b & c & d \\
    a & b & c & d \\
    a & b & c & d \\
    a & b & c & d
  \end{array}\right] = A
$

\end{document}
Community
  • 1
Werner
  • 603,163
4

A Little bit easier!

\documentclass[a4paper,11pt]{article}

\usepackage{amsmath}
\usepackage{color}

\begin{document}

\[
A =
\def\b{b}
\def\d{d}
\def\a{\color{red}a}
\def\c{\color{red}c}
\begin{bmatrix}
\a & \b & \c & \d \\
\a & \b & \c & \d \\
\a & \b & \c & \d \\
\a & \b & \c & \d \\
\end{bmatrix}
\]

\end{document}

enter image description here

  • 1
    I'm sure the OP made the matrix A have similar rows out of ease for a minimal example. In general, how would your suggestion be "easier" if the columns had arbitrary content in them? – Werner Jan 26 '17 at 20:06
  • @Werner: I don't claim to offer something generic. My assumption was this is what the OP needs, inherently. Actually, I was not as sure as you are! :D –  Jan 26 '17 at 20:10
  • Werner is right. However, thank you for your answer @Roboticist. It can be useful for another purpose ! – Thanasis1101 Jan 26 '17 at 20:18
2

Based on How to color math symbols? or Simpler way to add color to equations in math mode? (I googled "math color latex").

\documentclass[a4paper,11pt]{article}

\usepackage{amsmath}

\usepackage{xcolor}

\begin{document}

\begin{equation}
A = \begin{bmatrix}
\textcolor{red}{a} & b & \textcolor{red}{c} & d \\
\textcolor{red}{a} & b & \textcolor{red}{c} & d \\
\textcolor{red}{a} & b & \textcolor{red}{c} & d \\
\textcolor{red}{a} & b & \textcolor{red}{c} & d \\
\end{bmatrix}
\end{equation}

\end{document}

enter image description here

Community
  • 1
Dr. Manuel Kuehner
  • 22,451
  • I wanted an automatic way to change the color of the columns (like the accepted answer), but thank you for your answer ! – Thanasis1101 Jan 26 '17 at 20:15