[texhax] LaTeX amsmath: two equations aligned left-right

Lars Madsen daleif at imf.au.dk
Mon Mar 28 11:26:11 CEST 2011

Olivier Cailloux wrote:
> Le 28/03/2011 10:24, Lars Madsen a écrit :
>> [snip]
>>>> I would not write it like that at all (and I would never use 
>>>> multline, it often ends up looking really bad, especiellay if one 
>>>> afterwards change the margins)
>>>> \documentclass[a4paper]{article}
>>>> \usepackage[utf8]{inputenc}
>>>> \usepackage{amssymb}
>>>> \usepackage{amsmath}
>>>> \usepackage{amsthm}
>>>> \usepackage{empheq}
>>>> \begin{document}
>>>> \section{Now better}
>>>> $\forall j \in J, a \in A, 1 \leq h \leq k-1 :$
>>>> \begin{empheq}[left=\empheqlbrace]{align}
>>>> &\frac{1}{M_j+ \delta_j} ((g_j(a) - g_j(b_h))+\delta_j)
>>>> \leq C_j(a, b_h);\\
>>>> &C_j(a,
>>>> b_h) \leq \frac{1}{M_j} (g_j(a) - g_j(b_h)) + 1.
>>>> \end{empheq}
>>>> \end{document}
>>>> The $\forall...$ is the premise (is that the correct word?) and I 
>>>> would not write that as a part of the equation it self, it is 
>>>> understood from the context that the equation is under those conditions
>>> Thanks for your suggestion. It is simple and it answers the question. 
>>> Is it possible to get rid of empheq (that's yet an other package I 
>>> would have to learn)? I guess no...
>>> Olivier
>> No, empheq is so far the only package with enough flexibility to 
>> create a numbered construction like this.
>> I would say that it and the mathtools package a good tools for your 
>> arsenal.
> Ok I'll have a look. Mathtools (http://www.ctan.org/pkg/mathtools) seems 
> very interesting. Thanks again.
> Olivier

empheq loads mathtools, so you will need them both.

I use mathtools the most of the two.

Since empheq can do 'evil' things, it can also when in combination with 
the ntheorem package to solve some endmarker placement problems.



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