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Equation Alignment causes several Errors

LaTeX Forum: Math & Science

Add tags Information and discussion about LaTeX's math and science related features (e.g. formulas, graphs).
Hello,

LaTeX tells me there are 12 errors in there :
Code: Select all  •  Open in online LaTeX editor
\begin{aligned}  $|a_n| \sim |b_n| &\iff |a_n| - |b_n| = o(|a_n|) \\&\iff \forall \varepsilon > 0, \exists N \in \mathbb{N}, \forall n \ge N, |a_n| - |b_n| \le \varepsilon |a_n|$\end{aligned}

I guess it is because of the stuff in the aligned environment, since it is the first time I use it. Could someone explain how to use it so that LaTeX does not detect errors ? (surprisingly LaTeX displays exactly what I want to make, but I like documents without errors :D)

Thank you ! :)
Last edited by localghost on Sun Jan 20th, 2013, edited 1 time in total.
Reason: Longer passages of source code are tagged as code block, not as in-line code.
Wenneguen

Posts: 4
Joined: Sun Jan 20th, 2013

Please always provide a self-contained and minimal example to make a problem comprehensible at all. This would also prevent others from guesswork and random shots.

The aligned environment only works in math mode, either in-line or display mode. Since you didn't provide a full example, one can only guess that you are perhaps looking for something like this.
Code: Select all  •  Open in online LaTeX editor
\documentclass[11pt]{article}\usepackage[T1]{fontenc}\usepackage{mathtools}  % loads »amsmath«\begin{document}  \begin{equation}    \begin{aligned}      |a_n| \sim |b_n| &\iff |a_n| - |b_n| = o(| :D a_n|) \\      &\iff \forall \varepsilon > 0, \exists N \in \mathbb{N}, \forall n \ge N, |a_n|-|b_n| \le \varepsilon |a_n|    \end{aligned}  \end{equation}\end{document}

And it's not necessary to activate in-line math mode ($…$) inside another math environment.

Best regards and welcome to the board
Thorsten
LaTeX Community Moderator

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localghost
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