How can I split an equation over two (or more) lines

Question

I am having the following equation:

\begin{equation}
  Q(\lambda,\hat{\lambda}) = -\frac{1}{2} P(O \mid \lambda ) \sum_s \sum_m \sum_t \gamma_m^{(s)} (t) \left( n \log(2 \pi ) + \log \left| C_m^{(s)} \right| + \left( \mathbf{o}_t - \hat{\mu}_m^{(s)} \right) ^T C_m^{(s)-1} \left(\mathbf{o}_t - \hat{\mu}_m^{(s)}\right) \right)
\end{equation}

which does not very well fit on one line. How can I split this over two lines? What I have in mind is that I specify the splitting place, and that the first line is left aligned and the second line right aligned to make clear that it is still the same equation.

The linebreak \\ does not work.

Answer 1

Use either breqn to break lines automatically or use amsmath and its many environments exactly for this purpose. For example, with breqn:

\documentclass{article}
\usepackage{breqn}
\begin{document}
\begin{dmath}
  Q(\lambda,\hat{\lambda}) = -\frac{1}{2} P{(O \mid \lambda )} \sum_s \sum_m \sum_t \gamma_m^{(s)} (t) \left( n \log(2 \pi ) + \log \left| C_m^{(s)} \right| + \left( \mathbf{o}_t - \hat{\mu}_m^{(s)} \right) ^T C_m^{(s)-1} \left(\mathbf{o}_t - \hat{\mu}_m^{(s)}\right) \right)
\end{dmath}
\end{document}

Note, the expression around \mid required braces to prevent it from breaking at this point; I'm sure there is a better way to do that; anyway, here's the output:

With amsmath, you need to specify the break points manually: (as others have also mentioned)

\usepackage{amsmath}
...
\begin{multline}
  A+B+C+ \\ +D+E+F 
\end{multline}

The users guide to amsmath is called amsldoc.pdf, but you can access it by typing texdoc amsmath on the command line. The main environments you'll use there would be align, split, and multline.

Answer 2

You can use multline or split provided by amsmath package.

• Use multline to split equations without alignment (first line left, last line right)
• Use split to split equations with alignment

Here are examples:

The corresponding source code is as follows:

(i).Use equation:
\begin{equation}
1+2+3+4+8x+7=1+2+3+4+4x+35 \\
\Rightarrow x=7
\end{equation}

(ii).Use \emph{multline} to split equations without alignment:
\begin{multline}
1+2+3+4+8x+7=1+2+3+4+4x+35 \\
\Rightarrow x=7
\end{multline}

(iii).Use \emph{split} to split equations with alignment
\begin{equation}
\begin{split}
1+2+3+4+8x+7 & =1+2+3+4+4x+35 \\
& \Rightarrow x=7
\end{split}
\end{equation}

For more info, you can refer to User’s Guide for the amsmath Package.

Answer 3

First line left, last line right—that is the multline environment:

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{multline}
  Q(\lambda,\hat{\lambda}) = -\frac{1}{2} P(O \mid \lambda ) \sum_s \sum_m \sum_t \gamma_m^{(s)} (t) \biggl( n \log(2 \pi ) \\
  + \log \left| C_m^{(s)} \right| + \left( \mathbf{o}_t - \hat{\mu}_m^{(s)} \right) ^T C_m^{(s)-1} \left(\mathbf{o}_t - \hat{\mu}_m^{(s)}\right) \biggr)
\end{multline}
\end{document}

Answer 4

I often have the same problem, but opt for left-aligning on subsequent lines. In any case, I would suggest using the amsmath align environment. If I wanted right-aligning, here's what I would try (with white space liberally applied):

\begin{align}
  Q(\lambda,\hat{\lambda})
  = -\frac{1}{2} P(O \mid \lambda )
    \sum_s \sum_m \sum_t \gamma_m^{(s)} (t)
    \Biggl( n\log(2\pi)
  \mspace{150mu}
  \notag\\
     + \log \left| C_m^{(s)} \right|
     + \left( \mathbf{o}_t - \hat{\mu}_m^{(s)} \right)^T C_m^{(s)-1}
     \left(\mathbf{o}_t - \hat{\mu}_m^{(s)}\right)
    \Biggr)
\end{align}

Remarks:

• I replaced the outermost parentheses with large fixed-size parentheses, \Biggl( and \Biggr); scale these according to your taste.
• The \mspace command adds horizontal space in math mode, on the first line. Thus, the first line is not so much left-aligned, as it is right-aligned with a fixed amount of white-space added at the end. Vary this according to taste as well.
• You can split your equation across several lines by employing \notag\\ several times where desired.
• If you would prefer the equation number to straddle the two lines, as opposed to being placed on the last line, nest the mathematics inside a split environment (and omit the \notag commands); this would otherwise work verbatim.

[Edited to stand alone as a response]

Answer 5

For future reference, when trying to remember the name for the multiline environment, which is very handy and does this automatically (or about as close to it as Latex can go) - just remember, it's multline:

\begin{multline}
 I want my awesome formula to split lines here \\ 
           so this next part is aligned to the right in the following line, looking smart. 
\end{multline}

Answer 6

The easiest way to do this is with the split command

\begin{equation}
\begin{split}
\vec{A} \cdot \vec{B} & = (A_x \hat{x} + A_y \hat{y}+ A_z\hat{z}) \cdot (B_x \hat{x} + B_y \hat{y}+ B_z\hat{z}) \\
& = A_xB_x(\hat{x} \cdot \hat{x}) + A_yB_y(\hat{y} \cdot \hat{y}) + A_zB_z (\hat{z} \cdot \hat{z}) \\
&= A_xB_x + A_yB_y+A_zB_z
\end{split}
\end{equation}

This will yield a nicely formatted three line equation:

Answer 7

One thing while working with multline if you are using \displaystyle is that you have to type it on each line otherwise you'll get an error

\begin{multline*}  
K=\displaystyle{\frac{1}{2}m_1 L_1^2 \dot{\theta_1}^2+\frac{1}{2} m_2[L_1^2 \dot{\theta_1}^2+L_2^2 \dot{\theta_2}^2+2 L_1 L_2 \dot{\theta_1}\dot{\theta_2}\cos(\theta_1-\theta_2)]} \\
 \displaystyle{+\frac{1}{2}m_3[L_1^2 \dot{\theta_1}^2+L_2^2 \dot{\theta_2}^2+L_3^2+ \dot{\theta_3}^2+2 L_1 L_2 \dot{\theta_1}\dot{\theta_2}\cos(\theta_1-\theta_2)}
\end{multline*}

Notice the \displaystyle for each new line

Answer 8

I'm not an expert in LaTeX, but I get nice results using equation* in each line and equation in the last one. For example:

\begin{equation*}
    \Delta H_{f_{comb}} + \Delta H_{T_0 \rightarrow T_1}^{aire} + \Delta H_{T_0 \rightarrow T_1}^{comb} = \sum_i{\left[h_{f}^{comb_i} + \int_{T_0}^{T_1}{C_{p}^{comb_i}(T)\cdot dT} + \right.}
\end{equation*}
\begin{equation}
    + \left.\left(\int_{T_0}^{T_1}{\left[C_{p}^{O_{2}}(T)+C_{p}^{N_{2}}(T)\cdot\frac{78}{21}+C_{p}^{Ar}(T)\cdot\frac{1}{21}\right]\cdot dT}\right)\cdot \left(x_i + \frac{y_i}{4}\right)\cdot (1+p_{extra})\right]\cdot n_{comb_i}
\end{equation}

Which gives me the following

You can then align the equations as you like.

And also, if you have any \left or \right brackets or parenthesis you can just close them or open them using \left. or \right.

Maybe this is way too complicated and there may be easier workarounds, but it works for me.

Answer 9

Kind of a hack solution (uses \hspace) from me which however, sticks to the amsmath alignat environment in order to maintain the alignment between the first and any further lines of the split equations. The first line (equation) in the attached image and the code is to indicate the alignment.

\begin{alignat}{1}
    \frac{d\tilde{x}}{dt} &= -(\tilde{x}+x_0)\{\tilde{x}^2 + (2x_0-2)\tilde{x} + (x_0^2-2x_0-\mu_0-\tilde{\mu})\} \nonumber \\      
    \frac{d\tilde{x}}{dt} &= -\{\tilde{x}^3 + (3x_0-2)\tilde{x}^2 + (3x_0^2-4x_0-\mu_0-\tilde{\mu})\tilde{x} \\
                          &{\hspace{12pt}} +(x_0^3 -2x_0^2 -x_0\mu_0 -x_0\tilde{\mu})\} \nonumber
\end{alignat}   

Answer 10

\documentclass[1pt]{article}

\begin{document}
\begin{tabular}{p{0.5cm}p{0.5cm}p{10cm}} 
K &=&  $\frac{1}{2} m_1 L_1^2 \dot{\theta_1}^2
+\frac{1}{2} m_2[L_1^2 \dot{\theta_1}^2
+L_2^2 \dot{\theta_2}^2
+2 L_1 L_2 \dot{\theta_1}\dot{\theta_2}\cos(\theta_1-\theta_2)]$\\ 
&&$ +\frac{1}{2}m_3[L_1^2 \dot{\theta_1}^2+L_2^2 \dot{\theta_2}^2+L_3^2+ \dot{\theta_3}^2+2 L_1 L_2 \dot{\theta_1}
\dot{\theta_2}\cos(\theta_1-\theta_2)]$\\
\end{tabular}
\end{document}

This does not need any packages. You could try. Please send me your response.