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Could you help to comment how to typeset matrix inside aligned environment ? The following code gives a lot of "Missing $ inserted" when pdflatex... Many thanks !

\documentclass{article}

\usepackage{amsmath}     

\begin{document}

\title{}         % Enter your title between curly braces
\author{}        % Enter your name between curly braces
\date{}          % Enter your date or \today between curly braces
\maketitle

$$ \begin{aligned}
a = \left(\begin{matrix}
a_{1}  \\
a_{2}  \\
a_{3}
\end{matrix}\right) \text{in the basis } \{\vec{e}_i\} \\

a = \left(\begin{matrix}
a'_{1}  \\
a'_{2}  \\
a'_{3}
\end{matrix}\right) \text{in the basis } \{\vec{\varepsilon}_i\}
\end{aligned}
$$ 

\end{document}
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  • 2
    the answer given is good. but it fails to mention that blank lines aren't allowed in any math environment. (this is for the purpose of syntax checking, and can't be changed.)
    – barbara beeton
    Apr 29, 2018 at 2:45
  • I need aligned inside $$ instead of align*. Could you help to suggest how to achieve this ?
    – SOUser
    Apr 29, 2018 at 3:28

1 Answer 1

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2

I'm not certain what final result you are after (in terms of the exact place you want alignment or whether this is a fragment of something larger), but you could use \begin{align*}... to set these equations:

    \begin{align*}
    a &= \left(\begin{matrix}
    a_{1}  \\
    a_{2}  \\
    a_{3}
    \end{matrix}\right) \text{in the basis } \{\vec{e}_i\} \\
    a &= \left(\begin{matrix}
    a'_{1}  \\
    a'_{2}  \\
    a'_{3}
    \end{matrix}\right) \text{in the basis } \{\vec{\varepsilon}_i\}
    \end{align*}

enter image description here

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3
  • 1
    shorter is \documentclass{article} \usepackage{amsmath} \begin{document} \begin{align*} a & = \begin{pmatrix} a_{1} \\ a_{2} \\ a_{3} \end{pmatrix} \text{ in the basis } \{\vec{e}_i\} \\ a &= \begin{pmatrix} a'_{1} \\ a'_{2} \\ a'_{3} \end{pmatrix} \text{ in the basis } \{\vec{\varepsilon}_i\} \end{align*} \end{document}
    – Zarko
    Apr 28, 2018 at 17:50
  • I need aligned inside $$ instead of align*. Could you help to suggest how to achieve this ?
    – SOUser
    Apr 29, 2018 at 3:27
  • 2
    @SOUser You should be able to replace \begin{align*} by \[ \begin{aligned} (and similar at the end) in the code block above to get the same result. As Barbara Beeton correctly pointed out, your error message resulted from the blank line in your original post.
    – John
    Apr 29, 2018 at 12:10

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