Take the 2-minute tour ×
TeX - LaTeX Stack Exchange is a question and answer site for users of TeX, LaTeX, ConTeXt, and related typesetting systems. It's 100% free, no registration required.

I want to type the following equations by aligning them through the equal sign, but it seems to be too long:

\begin{align*}\prod_{z^n=-1}(w_1(z)^n+1)
&=& \prod_{l=0}^{l_0}(w_1(e^{\frac{(2l+1)\pi i}{n}})^n+1)\prod_{l=l_0+1}^{l_1}(w_1(e^{\frac{(2l+1)\pi i}{n}})^n+1)\times\prod_{l=l_1+1}^{n-1}(w_1(e^{\frac{(2l+1)\pi i}{n}})^n+1)\\
&=& \prod_{l=0}^{l_0}(w_1(e^{\frac{(2l+1)\pi i}{n}})^n+1)\prod_{l=l_0+1}^{l_1}(w_1(e^{\frac{(2l+1)\pi i}{n}})^{-n}+1)\times\prod_{l=l_1+1}^{n-1}(w_1(e^{\frac{(2l+1)\pi i}{n}})^n+1)\prod_{l=l_0+1}^{l_1}(w_1(e^{\frac{(2l+1)\pi i}{n}})^n)
\end{align*}

Someone can help me? Thanks a lot!

share|improve this question
2  
Please always post a complete small document not just a fragment, it helps those trying to help and "too long" depends on the current page size, and fonts, which you haven't shown. align unlike eqnarray should just have &= not &=& –  David Carlisle Aug 23 '13 at 16:04
add comment

3 Answers 3

up vote 1 down vote accepted

Just another way:

\documentclass[preview,border=12pt]{standalone}
\usepackage{mathtools}
\begin{document}
\abovedisplayskip=0pt\relax
\begin{align*}
\prod_{z^n=-1}(w_1(z)^n+1)
&=\!
    \begin{aligned}[t]
        &\prod_{l=0}^{l_0}(w_1(e^{\frac{(2l+1)\pi i}{n}})^n+1)
        \prod_{l=l_0+1}^{l_1}(w_1(e^{\frac{(2l+1)\pi i}{n}})^n+1) \\
        &\rule{10cm}{0pt}\mathllap{\times\prod_{l=l_1+1}^{n-1}(w_1(e^{\frac{(2l+1)\pi i}{n}})^n+1)}
    \end{aligned} \\
&=\!
    \begin{aligned}[t]
        &\prod_{l=0}^{l_0}(w_1(e^{\frac{(2l+1)\pi i}{n}})^n+1)
        \prod_{l=l_0+1}^{l_1}(w_1(e^{\frac{(2l+1)\pi i}{n}})^{-n}+1) \\
        &\rule{10cm}{0pt}\mathllap{\times\prod_{l=l_1+1}^{n-1}(w_1(e^{\frac{(2l+1)\pi i}{n}})^n+1)
        \prod_{l=l_0+1}^{l_1}(w_1(e^{\frac{(2l+1)\pi i}{n}})^n)}
    \end{aligned}
\end{align*}
\end{document}

enter image description here

Note: \! is needed before aligned because of the issue discussed in Why is there a \, space at the beginning of the “aligned” environment?.

share|improve this answer
add comment

You could use the multlined environment from the mathtools package.

\documentclass[11pt]{article}
\usepackage{mathtools}
\begin{document}
\begin{align*}\prod_{z^n=-1}(w_1(z)^n+1)&=
\begin{multlined}[t]
 \prod_{l=0}^{l_0}(w_1(e^{\frac{(2l+1)\pi i}{n}})^n+1)
 \prod_{l=l_0+1}^{l_1}(w_1(e^{\frac{(2l+1)\pi i}{n}})^n+1) \\
   \times\prod_{l=l_1+1}^{n-1}(w_1(e^{\frac{(2l+1)\pi i}{n}})^n+1)
\end{multlined} \\
&=
\begin{multlined}[t]
  \prod_{l=0}^{l_0}(w_1(e^{\frac{(2l+1)\pi i}{n}})^n+1)
  \prod_{l=l_0+1}^{l_1}(w_1(e^{\frac{(2l+1)\pi i}{n}})^{-n}+1) \\
     \times\prod_{l=l_1+1}^{n-1}(w_1(e^{\frac{(2l+1)\pi i}{n}})^n+1)    
     \prod_{l=l_0+1}^{l_1}(w_1(e^{\frac{(2l+1)\pi i}{n}})^n)
\end{multlined}
\end{align*}
\end{document}

You may want to change the location of the line breaks, depending on your font size, page width, etc.

big equation

share|improve this answer
    
Don't forget the \! before the multlined to cancel the mysterious extra space that you can see after the equals signs (there is a question about this somewhere, which I can't find). –  Ryan Reich Aug 23 '13 at 17:55
    
For readability I don't think the \times items should be indented that excessively. –  daleif Aug 23 '13 at 18:14
    
@RyanReich: The link you want to find has been added to my answer. –  Please don't touch Aug 24 '13 at 2:56
add comment

If it is too long you have to split the line in two pieces

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{align*}
\prod_{z^n=-1}(w_1(z)^n+1) &= \prod_{l=0}^{l_0}(w_1(e^{\frac{(2l+1)\pi i}{n}})^n+1)\prod_{l=l_0+1}^{l_1}(w_1(e^{\frac{(2l+1)\pi i}{n}})^n+1)\times\\
&\qquad\times\prod_{l=l_1+1}^{n-1}(w_1(e^{\frac{(2l+1)\pi i}{n}})^n+1)\\
&= \prod_{l=0}^{l_0}(w_1(e^{\frac{(2l+1)\pi i}{n}})^n+1)\prod_{l=l_0+1}^{l_1}(w_1(e^{\frac{(2l+1)\pi i}{n}})^{-n}+1)\times\\
&\qquad\times\prod_{l=l_1+1}^{n-1}(w_1(e^{\frac{(2l+1)\pi i}{n}})^n+1)\prod_{l=l_0+1}^{l_1}(w_1(e^{\frac{(2l+1)\pi i}{n}})^n)
\end{align*}
\end{document}

enter image description here

share|improve this answer
1  
In western trasition the \times symbols are not duplicated, the one ending a line is not used. –  daleif Aug 23 '13 at 18:13
    
Thank you so much! –  mapping Aug 23 '13 at 18:15
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.