# break a long equation with an initial bracket [duplicate]

I tried to fix this problem by reading the answers to the questions on this forum related to this topic, but I did not find any solution. Could you help me, please? The thing is that I have to break a long equation with an initial bracket...Because of that, I am not able to use neither split nor align...Here the text

$$u_{i}^{n+1} = \frac{1}{2} \hat u_m^n e^{Ii\phi_m} \left\{ \frac{1}{2} \left(e^{I\phi_m}+e^{-I\phi_m}+2\right) -\frac{\Gamma}{2} \left(e^{I\phi_m} + e^{-I\phi_m}\right) - \Gamma \left[ \frac{1}{2} \left(e^{I\phi_m} + e^{-I\phi_m}\right) - \frac{\Gamma}{2} \left(e^{I\phi_m} + e^{-I\phi_m} -2\right)\right] \right\}. \notag$$

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## marked as duplicate by Peter Jansson, Jubobs, cmhughes, barbara beeton, GuidoJan 30 '14 at 19:34

Possible duplicate: Left/Right across multiline equation – Werner Jan 30 '14 at 17:51
The (easiest) suggested solution in this case is to use \big-style delimiters... – Werner Jan 30 '14 at 17:51
ie write \bigl\{ instead of \left\{ and \bigr\} instead of \right\}. Then you can put it in a split. – Thruston Jan 30 '14 at 17:53

It seems that the terms in your equation have the same height. This means that TeX can estimate the braces height from any of them. Therefore the construction

 \left\{ ....  \right.\\
\left.  ....  \right\}


works right (otherwise we would need to put the delimiter sizes explicitly or to use \vphantom{THE_HIGHEST_TERM} in the corresponding line).

This works:

\documentclass{article}
\usepackage{amsmath}
\pagestyle{empty}
\begin{document}

\begin{multline}
u_{i}^{n+1} = \frac{1}{2} \hat u_m^n e^{Ii\phi_m} \left\{ \frac{1}{2}
\left(e^{I\phi_m}+e^{-I\phi_m}+2\right)
-\frac{\Gamma}{2} \left(e^{I\phi_m} + e^{-I\phi_m}\right) -
\right.\\
\left.
\Gamma \left[ \frac{1}{2} \left(e^{I\phi_m} + e^{-I\phi_m}\right) -
\frac{\Gamma}{2} \left(e^{I\phi_m} + e^{-I\phi_m} -2\right)\right]
\right\}. \notag
\end{multline}

\end{document}


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