# Align matrix on left margin. align* left-aligned?

I have the following problem: I put the command vmatrix inside the align* area. The result is unfortunately centered, but I'd like to have the matrix be left-aligned.

Here is the code:

\documentclass[11pt,a4paper]{report}
\usepackage{amsmath}
\begin{document}

\begin{align*}
\begin{vmatrix}
f(x_0=0) & = & a_0 \\
f'(0) & = & a_1 \\
f''(0) & = & 2\cdot a_2 \\
& \vdots & \\
f^{(n)}(0) & = & n! \cdot a_n
\end{vmatrix}
&  \Rightarrow  a_n = \frac{f^{(n)}(0)}{n!}
\end{align*}

\end{document}


How can I put the matrix on the left margin?

• Welcome to TeX.SE. You need to (a) load amsmath with the option fleqn and (b) execute \setlength\mathindent{0pt} before the start of the align* environment. – Mico Apr 11 '16 at 19:50
• Welcome to TeX.SX! Usually, we don't put a greeting or a “thank you” in our posts. While this might seem strange at first, it is not a sign of lack of politeness, but rather part of our trying to keep everything very concise. Accepting and upvoting answers is the preferred way here to say “thank you” to users who helped you. – Martin Schröder Apr 11 '16 at 20:05
• @Mico -- answer, please. – barbara beeton May 8 '16 at 20:43

To make the displayed equation start hard at the left edge of the text block, you should (a) load the amsmath package with the option fleqn (short for "flush left equation", I suppose) and (b) set the \mathindent length parameter to 0pt.

\documentclass[11pt,a4paper]{report}

\usepackage[fleqn]{amsmath}
\setlength\mathindent{0pt}

\begin{document}
\begin{align*}
\begin{vmatrix}
f(x_0=0) & = & a_0 \\
f'(0) & = & a_1 \\
f''(0) & = & 2\cdot a_2 \\
& \vdots & \\
f^{(n)}(0) & = & n! \cdot a_n
\end{vmatrix}
&  \Rightarrow  a_n = \frac{f^{(n)}(0)}{n!}
\end{align*}
\end{document}