# How can I separate an equation over two or three lines?

I am having the following equation as below

$$\label{eq:36} \emph{SINR^{D,UL}_{k,n}} = \frac{p_{k,n} |h_{k,n}|^2}{\sum_{m=1}^{M} \omega_{n,m}p_{m,n}|h^{C}_{m,n}|^2 + \sum_{c^{'}=1}^{C^{'}} \sum_{m^{'}}^{M^{'}} \omega^{'}_{n,m^{'},c^{'}}p_{m^{'},n}|h^{C}_{m^{'},n,k,c^{'}}|^2 + \sum_{c^{'}=1}^{C^{'}} \sum_{k^{'}}^{K^{'}} \zeta^{'}_{n,k^{'},c^{'}}p_{k^{'},n}|h^{D}_{k^{'},n,k,c^{'}}|^2 + N_{0}B}$$


The equation does not very well fit on one line. How can I separate this over two or three lines? Please see my figure example.

Thanks a lot.

Perhaps use multline?

\documentclass{article}
\usepackage{amsmath}
\newcommand\abs[1]{\lvert#1\rvert}
\begin{document}

\begin{multline}
\label{eq:36}
\mathrm{SINR}^{D,UL}_{k,n} =  p_{k,n} \abs{h_{k,n}}^2
\biggl(
\sum_{m=1}^{M} \omega_{n,m} p_{m,n} \abs{h^{C}_{m,n}}^2 \\
+ \sum_{c'=1}^{C'} \sum_{m'}^{M'} \omega'_{n,m',c'} p_{m',n} \abs{h^{C}_{m',n,k,c'}}^2 \\
+ \sum_{c'=1}^{C'} \sum_{k'}^{K'} \zeta'_{n,k',c'} p_{k',n} \abs{h^{D}_{k',n,k,c'}}^2
+ N_{0}B
\biggr)^{\!-1}
\end{multline}

\end{document}


Or introduce aliases:

\documentclass{article}
\usepackage{amsmath}
\newcommand\abs[1]{\lvert#1\rvert}
\begin{document}

$$\label{eq:36} \mathrm{SINR}^{D,UL}_{k,n} = \frac{p_{k,n} \abs{h_{k,n}}^2}{X + Y + Z + N_{0}B}$$
where
\begin{align*}
X &= \sum_{m=1}^{M} \omega_{n,m} p_{m,n} \abs{h^{C}_{m,n}}^2 \\
Y &= \sum_{c'=1}^{C'} \sum_{m'}^{M'} \omega'_{n,m',c'} p_{m',n} \abs{h^{C}_{m',n,k,c'}}^2 \\
Z &= \sum_{c'=1}^{C'} \sum_{k'}^{K'} \zeta'_{n,k',c'} p_{k',n} \abs{h^{D}_{k',n,k,c'}}^2
\end{align*}

\end{document}


You can also make that nasty thing you showed in the question, but I do not recommend that.

\documentclass{article}
\usepackage{amsmath}
\newcommand\abs[1]{\lvert#1\rvert}
\begin{document}

$$\label{eq:36} \mathrm{SINR}^{D,UL}_{k,n} = \frac{p_{k,n} \abs{h_{k,n}}^2}{ \begin{pmatrix} \sum_{m=1}^{M} \omega_{n,m} p_{m,n} \abs{h^{C}_{m,n}}^2 + {} \\ \sum_{c'=1}^{C'} \sum_{m'}^{M'} \omega'_{n,m',c'} p_{m',n} \abs{h^{C}_{m',n,k,c'}}^2 + {} \\ \sum_{c'=1}^{C'} \sum_{k'}^{K'} \zeta'_{n,k',c'} p_{k',n} \abs{h^{D}_{k',n,k,c'}}^2 + N_{0}B \end{pmatrix} }$$

\end{document}


• Great! I like the last one example as you suggested. Thanks a lot to @Henri Menke – user3727281 May 22 '17 at 21:58
• Mmmhh… :-( \substack is meant for super/subscripts, and for this reason it typesets its argument in \scriptstyle; note that this entails that you get no space around binary operators and relation symbols. What about a pmatrix environment, instead? It usesn\textstyle, which seems much more appropriate… Also, I guess you didn’t notice the ^{'} idiom that the OP uses repeatedly, |...| instead of \lvert ... \rvert, or better, \DeclarePairedDelimiter – GuM May 22 '17 at 23:16
• @user3727281 Why are you picking the garbage solution when I presented two other perfectly reasonable ones? – Henri Menke May 22 '17 at 23:23
• @GustavoMezzetti You are right. I didn't put too much effort into it. Using pmatrix instead of \substack is a good. I wouldn't say a substack is completely wrong here because somehow you need to cramp all that stuff in the denominator but then this part is ugly anyway and cannot be made looking decent. – Henri Menke May 22 '17 at 23:39