# long equation in two column paper (the mathtool doesnt work.)

I have an equation which is too long for a two-column paper. the code that I write is like below :

\begin{equation*}
\begin{split}
J=\frac{\displaystyle -l_2}{\displaystyle sin(\theta_3-\theta_2)}\cdot
\begin{matrix}
sin(\theta_1)sin(\theta_3-\theta_2)+sin(\theta_2)sin(\theta_1-\theta_3)&-sin(\theta_2)sin(\theta_4-\theta_3)\\
-cos(\theta_1)sin(\theta_3-\theta_2)-cos(\theta_2)sin(\theta_1-\theta_3)&cos(\theta_2)sin(\theta_4-\theta_3)
\end{matrix}
\end{split}
\end{equation*}


but it doesn't work.what can i do?

• Welcome to TeX.SX! Please help us help you and add a minimal working example (MWE) that illustrates your problem. Reproducing the problem and finding out what the issue is will be much easier when we see compilable code, starting with \documentclass{...} and ending with \end{document}. – user31729 Jul 14 '15 at 9:14

The best approach would be to introduce some new symbols such as Z=\sin(\theta_3-\theta_2) in order to get it easier to read and shorter to typeset.

Assuming that you need all those terms in one equation, you could possibly do like the following:

% arara: pdflatex

\documentclass[twocolumn]{article}
\usepackage{mathtools}
\usepackage{blindtext}

\begin{document}
\blindtext
\begin{multline*}
J=\frac{-l_2}{\sin(\theta_3-\theta_2)}\cdot \\
\begin{bmatrix}
\end{bmatrix}
\end{multline*}
\blindtext
\end{document}


For maximum readability, you may put the equation at the bottom of the page like this (without the need to modify the equation at all):

\documentclass{article}
\usepackage{multicol,amsmath,lipsum}
\usepackage[margin=2cm]{geometry}
\begin{document}
\begin{multicols}{2} %
\enlargethispage{-2cm}

\begin{picture}(0,0)
\put(0,-600){\hspace{-\parindent}\parbox{\textwidth}{%
\hrulefill
\vspace*{4pt}
\begin{equation*} \label{eqn_first}
J=\frac{\displaystyle -l_2}{\displaystyle sin(\theta_3-\theta_2)}\cdot\
\begin{bmatrix}
sin(\theta_1)sin(\theta_3-\theta_2)+sin(\theta_2)sin(\theta_1-\theta_3)&-sin(\theta_2)sin(\theta_4-\theta_3)\\
-cos(\theta_1)sin(\theta_3-\theta_2)-cos(\theta_2)sin(\theta_1-\theta_3)&cos(\theta_2)sin(\theta_4-\theta_3)
\end{bmatrix}
\end{equation*}}}
\end{picture}%
\enlargethispage{-2cm}
\lipsum[1-6]
\lipsum[2-5]

\end{multicols}
\end{document}


We have to shrink the remaining text to leave room for the equation by \enlargethispage{-2cm}. You can control the space as needed. There is also a widetext package that you could try.

Another good option is to use shortcuts by introducing new symbols:

\lipsum[1-6]
\begin{equation*}
J=\frac{\displaystyle -l_2}{\displaystyle sin(\theta_3-\theta_2)}\cdot\
\begin{bmatrix}
A & B\\
C & D
\end{bmatrix}
\end{equation*}
where,

$A=sin(\theta_1)sin(\theta_3-\theta_2)+sin(\theta_2)sin(\theta_1-\theta_3)$

$B=sin(\theta_2)sin(\theta_4-\theta_3)$

$C=-cos(\theta_1)sin(\theta_3-\theta_2)-cos(\theta_2)sin(\theta_1-\theta_3)$

$D=cos(\theta_2)sin(\theta_4-\theta_3)$

\lipsum[2-5]


• Very nice, but please use \sin\cos. If you put the last example in align, you can use \shortintertext{where,} from mathtools and get much better spacing. – LaRiFaRi Jul 14 '15 at 11:30