# How to split an equation over two lines?

I am new to LaTeX,

Here is my formula,

\documentclass{article}
\begin{document}
$$\small{ \Delta (h)_{T+S} = \prod_{j=1}^{N} \left[\frac {P(x^j,y^j|\theta_{paired})} {P(x^j,y^j|\theta_{unpaired})}\right]\left[\frac{P(bp)_{x^j,y^j} P(bp_{x^j,y^j}|pbp_{x^{j-1},y^{j+1}}) P(dl_{x^j}) P(dl_{x^j}|pdl_{x^{j-1}})P(dr_{y^j})P(dr_{y^j}|pdr_{y^{j+1}})}{P(sl) P(dl|sl) P(sr) P(dr|sr)}\right]}$$
\end{document}


I want the equation to be split over two lines, how can I do this? I tried, multline, align*, split, alignedat, nothing seems to work. Please help me with this. Thank you in advance.

• Welcome to TeX.SE. – Sebastiano Jun 20 at 20:14
• How wide is the textblock? (Alternatively, please tell us which paper size is employed, and how wide the margins are.) – Mico Jun 21 at 3:01

Here there is my proposal to split your equation.

EDIT: The slight change in my code is due an additional \cdot.

\documentclass{article}
\usepackage[margin=2cm]{geometry}
\usepackage{mathtools,amssymb}
\begin{document}
$$\begin{split} \Delta (h)_{T+S} & =\prod_{j=1}^{N} \left[\frac {P(x^j,y^j|\theta_{\mathrm{paired}})} {P(x^j,y^j|\theta_{\mathrm{unpaired}})}\right] \\ & \cdot \left[\frac{P(bp)_{x^j,y^j} P(bp_{x^j,y^j}|pbp_{x^{j-1},y^{j+1}}) P(dl_{x^j}) P(dl_{x^j}|pdl_{x^{j-1}})P(dr_{y^j})P(dr_{y^j}|pdr_{y^{j+1}})}{P(sl) P(dl|sl) P(sr) P(dr|sr)}\right] \end{split}$$
\end{document}

• Thank you so much, this works fine. – User Jun 20 at 20:14
• This is unusual typesetting. You've put the line break in a sensible place, but I've never seen anybody write the operator on both lines. blah \cdot \\ blah or blah \\ \cdot blah are normal. – David Richerby Jun 21 at 14:35
• @DavidRicherby blogs.msdn.microsoft.com/murrays/2007/09/01/… suggests that this is "popular in Russian mathematical typography". – Marcel Krüger Jun 22 at 9:18

The brackets are surplus here, the fraction is a group by itself, so you don't need extra grouping. If I use brackets, I will enclose the whole formula to the right of the = sign into a pair of brackets. I also used \biggl[ and \biggr] for easy splitting. Finally, as @Sebastiano suggested, use \mathrm for text.

Note: you didn't tell us how thick the margins are, so I assumed 1in. If my answer is still too wide, uncomment the \small block.

\documentclass{article}
\usepackage{amsmath}
\usepackage[margin=1in]{geometry}

\begin{document}

%{\small
$$\begin{split} \Delta (h)_{T+S} &= \prod_{j=1}^{N} \biggl[\frac {P(x^j,y^j|\theta_\mathrm{paired})} {P(x^j,y^j|\theta_\mathrm{unpaired})} \times{} \\ &\phantom{{}={}}\frac{P(bp)_{x^j,y^j} P(bp_{x^j,y^j}|pbp_{x^{j-1},y^{j+1}}) P(dl_{x^j}) P(dl_{x^j}|pdl_{x^{j-1}})P(dr_{y^j})P(dr_{y^j}|pdr_{y^{j+1}})}{P(sl) P(dl|sl) P(sr) P(dr|sr)}\biggr] \end{split}$$
%}

\end{document}


• I'm a little late for a positive vote on your good work. – Sebastiano Jun 20 at 20:52
• Thank you, you were the fastest. – AboAmmar Jun 20 at 20:57
• If possible, I'd push the second line to the right so it began to the right of the product sign. That would visually cue that it's a part of the product (though the brackets and the presence of $j$s in the second line do make this semantically clear). – David Richerby Jun 21 at 14:36

A way to put the equation on a single line, with the \splitfrac command from mathtools, the \medmath command from nccmath and some adjustment for the delimiters:

\documentclass{article}
\usepackage[margin=2cm]{geometry}
\usepackage{mathtools, nccmath, amssymb}

\begin{document}

$$\Delta (h)_{T+S} =\prod_{j=1}^{N} \left[\frac {P(x^j,y^j\mid\theta_{\mathrm{paired}})} {P(x^j,y^j\mid\theta_{\mathrm{unpaired}})}\right]\cdot \left[\frac{\medmath{\splitfrac{P(bp)_{x^j,y^j} P\bigl(bp_{x^j,y^j}\mid pbp_{x^{j-1},y^{j+1}}\bigr)P(dl_{x^j}) }{ P(dl_{x^j}\mid pdl_{x^{j-1}})P\bigl(dr_{y^j}\bigr)P\bigl(dr_{y^j}\mid pdr_{y^{j+1}}\bigr)\rule[-1.5ex]{0pt}{1ex}}}}{P(sl) P(dl|sl) P(sr) P(dr| sr)^{\strut} }\right]$$

\end{document}


• I know the command \splitfrac but I did not want to use it because it is not my favorite. +1 – Sebastiano Jun 20 at 20:59
• @Sebastiano: I think it mainly depends on the case at hand. Here, combined with \medmath and some vertical space tweaking, I find it doesn't look so bad – Bernard Jun 20 at 21:04
• De gustibus non disputandum est: There's no discussion of the tastes. :-) – Sebastiano Jun 20 at 21:10
• Needless to translate – when I was a student, I helped some highschool students in Latin ;o) – Bernard Jun 20 at 21:16

one more alternative, with use of mathtools and nccmath:

\documentclass{article}
\usepackage{geometry}
\usepackage{mathtools, nccmath}

%---------------- show page layout. don't use in a real document!
\usepackage{showframe}
\renewcommand\ShowFrameLinethickness{0.15pt}
\renewcommand*\ShowFrameColor{\color{red}}
%---------------------------------------------------------------%
\begin{document}
$$\medmath{ \begin{multlined} \Delta (h)_{T+S} = \prod_{j=1}^{N} \Biggl[\frac{P(x^j,y^j\mid\theta_{\mathrm{paired}})} {P(x^j,y^j\mid\theta_{\mathrm{unpaired}})}\Biggr]\\ \cdot \Biggl[\frac{P(bp)_{x^j,y^j} P(bp_{x^j,y^j}\mid pbp_{x^{j-1},y^{j+1}}) P(dl_{x^j}) P(dl_{x^j}\mid pdl_{x^{j-1}})P(dr_{y^j})P(dr_{y^j}|pdr_{y^{j+1}})} {P(sl) P(dl\mid sl) P(sr) P(dr\mid sr)}\Biggr] \end{multlined} }$$
\end{document}


• Fast as lightning...:-) +1. – Sebastiano Jun 20 at 20:51

Here's a multlined-based solution. It also uses \mid rather than | to denote conditioning, and it "snugs up" the subscript terms to dr.

\documentclass{article}
\usepackage[a4paper,margin=2.5cm]{geometry} % make suitable page and margin choices
\usepackage{mathtools} % for 'multlined' environment

\begin{document}

$$\renewcommand{\!}{\mkern-2mu} % default: \mkern-3mu \begin{multlined} \Delta(h)_{T+S} = \prod_{j=1}^{N} \biggl[ \frac {P(x^j\!,y^j\mid \theta_{\mathrm{paired}})}{% P(x^j\!,y^j\mid \theta_{\mathrm{unpaired}})}\\ \times \frac{P(bp)_{x^j\!,y^j} P(bp_{x^j\!,y^j}\mid pbp_{x^{j-1}\!,y^{j+1}}) P(dl_{x^j}) P(dl_{x^j}\mid pdl_{x^{j-1}}) P(dr_{\!y^j})P(dr_{\!y^j}\mid pdr_{\!y^{j+1}})}{% P(sl) P(dl\mid sl) P(sr) P(dr\mid sr)} \biggr] \end{multlined}$$
\end{document}


With multiline one can insert \\ at the locations where the line should be broken.

Multiletter subscripts ought not be set in math italics, the kerning is wrong. I suggest to warp them in \mathrm{}

The fontsize change needs to be outside the equation and without {} following it. \small was still a bit to large, but with \footnotesize the equation fits even without cheating and changing the margin sizes.

\documentclass{article}
\usepackage{amsmath}

\begin{document}

{
\footnotesize
\begin{multline}
\Delta (h)_{T+S} =
\prod_{j=1}^{N} \left[\frac {P(x^j,y^j|\theta_{\mathrm{paired}})}
{P(x^j,y^j|\theta_{\mathrm{unpaired}})}\right]\cdot\\
\left[\frac{P(bp)_{x^j,y^j}
P(bp_{x^j,y^j}|pbp_{x^{j-1},y^{j+1}}) P(dl_{x^j})
P(dl_{x^j}|pdl_{x^{j-1}})P(dr_{y^j})P(dr_{y^j}|pdr_{y^{j+1}})}{P(sl)
P(dl|sl) P(sr) P(dr|sr)}\right]
\end{multline}
}

\end{document}


• Thanks you so much, this works fine as well. – User Jun 20 at 20:15
• @ShilpaJanarthanan Was my pleasure! – gigi Jun 20 at 20:15
• Can you please tell me, how to add \cdot in the above code, to show the continuity of the equation? – User Jun 20 at 20:24
• @ShilpaJanarthanan Please check now. Also please don't have whole words in math italic. – gigi Jun 20 at 20:30