# Latex question

1. ### kdv

329
I am not sure if this is the right place to post a Latex question. If not, tell me where I should go.

I would like to put equations inside a box. Now, I have found two ways to do this butthey work only for single line equations. The best method is to simply put the equations between boxed braces, i.e. \boxed{ equation}

this works if I am in an equation array i.e.

$$\boxed{equation}$$

I have tried the same thing in an eqnarray but I get compilations errors. I would like to have equations spanning several lines which would be inside a box.

Anybody can help?

Thanks

2. ### OmCheeto

2,029
There are instructions in the LaTeX thread here at the forum. I haven't read the entire thing. There are over 700 posts.

3. ### kdv

329
I found a way but I am not sure if it will work on the forums here, so here's the trick:
$$\begin{equation*} \addtolength{\fboxsep}{5pt} \boxed{ \begin{gathered} \Pi_{i=1}^m \int d^4x_i \, e^{-i (k \cdot x)_i} ~\Pi_{j=1}^n \int d^4y_j \, e^{+ i (p \cdot y)_j} \\ <0| T\{ \phi(x_1) \ldots \phi(x_m) \phi(y_1) \ldots \phi(y_n) \} |0> \\ = \biggl( \Pi_{i=1}^m \frac{i \sqrt{Z}}{k_i^2 - m^2} \biggr) \biggl(\Pi_{j=1}^n \frac{i \sqrt{Z}}{p_j^2 - m^2} \biggr) ~<\vec{p}_1 \ldots \vec{p_n}|i T| \vec{k_1} \ldots \vec{k_m}> \end{gathered} } \end{equation*}$$

It worked!!!!!!

(For anybody interested, left click on the equation to see the source code)

4. ### Bob505

1
Thanks a lot for this tip kdv I'd been wondering how to get boxes around multiline equations.

Also, for alignment you can use the 'split' environment rather than 'gathered'.

$$\begin{equation*} \addtolength{\fboxsep}{10pt} \boxed{ \begin{split} \int \frac{d^D P}{(2\pi)^D} \frac{{\cal P}_n(P)} {P^{2\alpha}(P-Q)^{2\beta}} = &\frac{1}{(4\pi)^2}(Q^2)^{D/2-\alpha-\beta}\sum_{\sigma \ge 0}^{[n/2]} G(\alpha,\beta,n,\sigma) \cdot \\ &\cdot Q^{2\sigma} \left\{ \frac{1}{\sigma !} \left( \frac {\Box} {4} \right) ^\sigma {\cal P}_n(P)\right\}_{P=Q} \end{split} } \end{equation*}$$

For anybody compiling this remember to include \usepackage{amsmath} in your preamble and for this particular example also \usepackage{amssymb} for the D'Alembertian.

Thanks again.