# How to align array inside align?

I wrote an array environment inside align. As array have a blank space around it, I cant align it properly.

I'm using array{l}, because I do want elements on the left inside array.

\documentclass[]{report}
\usepackage{amsmath}

\begin{document}
\begin{align*}
a=&a
\\
a=&\begin{array}{l}
bb
\\
ccc
\end{array}
\end{align*}
\end{document}


• One suggestion: could you perhaps change the title of your question to How to align entries of a matrix? That way it may get more attention, and I do not think that the problem is related to the math environment align. But this is all up to you.
– user121799
May 12, 2018 at 4:09
• Try \begin{array}{@{}l@{}}. May 12, 2018 at 4:16

Now I think to understand what you want: the matrix* environment from the mathtools package.

\documentclass[]{report}
\usepackage{amsmath}
\usepackage{mathtools}
\begin{document}
\begin{align*}
a&=aaaa
\\
a&=\begin{matrix*}[l]
bbb
\\
cc
\end{matrix*}
\end{align*}
\end{document}


• I didnt explain well enough and my example was poor. It should be left aligned and elements have different size. Matrix are centered. May 12, 2018 at 3:14
• I updated my question. Maybe I have a solution with \hspace[-5pt] but I dont know if it is a general solution May 12, 2018 at 3:18
• Your matrix is centered. as you see in my question, I use array{l}. I made an answer myself using hspace, I just dont know if it is a general solution. May 12, 2018 at 3:33
• Now you made it general. I have already seen solutions like yours on pmatrix, but it didnt work on matrix. I didnt know things changed on matrix* environment. May 12, 2018 at 3:44
• The spacing around = is wrong. It should be &= May 12, 2018 at 9:34

\documentclass[]{report}
\usepackage{amsmath}

\begin{document}
\begin{align*}
a&=a
\\
a&=\begin{array}{@{}l@{}}
bb
\\
ccc
\end{array}
\end{align*}
\end{document}


For correct spacing around the = sign, the & should go in front of it.