# Float matrix left among other matrices

I'd like to float one matrix left among the others, and make the text grey. Currently, I can only simulate this by adding the correct \hspace*{} after my first matrix that I would like to align left.
My current code looks like such,

 \documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{mathtools}
\usepackage{amsmath}
\usepackage{amssymb}
\DeclarePairedDelimiter\ket{\lvert}{\rangle}
\begin{document}
$$\begin{matrix} \ket{11}\\ \ket{01}\\ \ket{10}\\ \ket{00} \end{matrix} \hspace*{50pt} \begin{pmatrix} 0\\ 0\\ 1\\ 0 \end{pmatrix} \begin{pmatrix} 0 & 0 & 1 & 0\\ 0 & 1 & 0 & 0\\ 1 & 0 & 0 & 0\\ 0 & 0 & 0 & 1 \end{pmatrix} = \begin{pmatrix} 1\\ 0\\ 0\\ 0 \end{pmatrix}$$
\end{document}


and yields the following

Concluding; how do I left align/float the first matrix and make the text grey?

• I suggest you to add those three or four lines to make the Minimal Example also Working, i.e. a MWE. If you make so, you'll help us to help you! – Enrico Maria De Angelis Nov 13 '16 at 11:33
• @EnricoMariaDeAngelis Sorry, I don't understand what you mean. What exactly should I add? – Isaiah Nov 13 '16 at 11:36
• I mean \documentclass, \begin{document}, needed packages... I could do it for you, but doing it by yourself will make you a better user! ;) – Enrico Maria De Angelis Nov 13 '16 at 11:37
• and used packages for this equations as well \begin{document} and end{document} ... – Zarko Nov 13 '16 at 11:38
• @EnricoMariaDeAngelis Updated! – Isaiah Nov 13 '16 at 11:40

Use the flalign environment and {\color{gray} ket matrix } (requires color or xcolor. Note you don't have to load amsmath since mathtools does it:

 \documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{xcolor} %
\usepackage{mathtools}%
\usepackage{amssymb}
\DeclarePairedDelimiter\ket{\lvert}{\rangle}
\begin{document}

\begin{flalign}
&{\color{gray} \begin{matrix}
\ket{11}\\
\ket{01}\\
\ket{10}\\
\ket{00}
\end{matrix}} %
& \begin{pmatrix}
0\\
0\\
1\\
0
\end{pmatrix}
\begin{pmatrix}
0 & 0 & 1 & 0\\
0 & 1 & 0 & 0\\
1 & 0 & 0 & 0\\
0 & 0 & 0 & 1
\end{pmatrix}
& =
\begin{pmatrix}
1\\
0\\
0\\
0
\end{pmatrix}
& & %
\end{flalign}

\end{document}


• Thank you! However, maybe you could mention this requires the xcolor package? – Isaiah Nov 13 '16 at 11:54
• I'll add it. But isn't it obvious any colour specification require requires a dedicated package – color or xcolor? – Bernard Nov 13 '16 at 11:56
• Well, one (new user) could think that one of these commands is in some automatically loaded package of the class or something similar... – Enrico Maria De Angelis Nov 13 '16 at 11:59

The xcolor package's \textcolor{<color>}{<text>} command could simply help you with the color. The {\color{<color>} text}, is another option, but I like the former more.