LyX ⇒ New line in equation

[luc4]

Hi! I would like to have an equation written on two lines (one is not sufficient), but boxed as a whole. This is what I have now:

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\[
\boxed{\iint_{\Omega}\left(a_{1}\nabla\upsilon\cdot\nabla\varphi+a_{0}\upsilon\varphi\right)d\boldsymbol{z}=}\]
\begin{equation}
\boxed{\iint_{\Omega}\left(f\varphi-a_{1}\nabla\gamma\cdot\nabla\varphi-a_{0}\gamma\varphi\right)d\boldsymbol{z}+\int_{\Gamma_{N}}\left(a_{1}g_{N}\varphi\right)d\boldsymbol{S},\;\forall\varphi\in H^{1}\left(\Omega\right)}.\label{eq:General-weak-formulation-explicit}\end{equation}

The problem is that this way I have two different boxes for the two different lines.
I tried using one equation only, but I'm not able to make a new line. I tried with C-Enter, but I got two lines with two different reference numbers... but I would like to have only one... its an equation only...
Is there any other way to have a single equation, with one single reference number, on two lines with a single box?
Thanks!

[Stefan Kottwitz]

Hi,

you could use a multiline environment of amsmath, for instance aligned:

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\begin{equation}
\boxed{\begin{aligned}
&\iint_{\Omega}\left(a_{1}\nabla\upsilon\cdot\nabla\varphi+a_{0}\upsilon\varphi\right)d\boldsymbol{z}=\\
&\iint_{\Omega}\left(f\varphi-a_{1}\nabla\gamma\cdot\nabla\varphi-a_{0}\gamma\varphi\right)d\boldsymbol{z}
+\int_{\Gamma_{N}}\left(a_{1}g_{N}\varphi\right)d\boldsymbol{S},\;\forall\varphi\in H^{1}\left(\Omega\right).\label{eq:General-weak-formulation-explicit}
\end{aligned}}
\end{equation}

Stefan

[luc4]

I'm trying to do this... but I'm not able to write the & symbol and the double backslash. If I write it with Lyx I get \& and \backslash... Maybe that's why I am not getting what I want...
Thanks for your answer!

[Stefan Kottwitz]

At least it should work if you put that complete code into a TeX environment (ERT).

Stefan

[luc4]

Yes, sure it works! Except I would like those lines to be aligned center.

The problem is that I would like to know if it is possible to do it using the equation editor of Lyx as it would be useful to have the equations written in the good looking format instead of the inline format. Simpler to see the mistakes and edit them.

Thanks again!