[OS X TeX] Using align with "or"

[Alain Schremmer]

On Apr 17, 2011, at 10:04 PM, Ross Moore wrote:

>
> On 18/04/2011, at 11:39 AM, Alain Schremmer wrote:
>
>>> Try  The LaTeX Companion    1st or 2nd editions.
>>
>> But Companion two does not even mention \alignat. I just looked  
>> because I had been "doing it by hand", that is with a lot of  
>> \hspaces, and wanted to know if I had missed it.
>
> You're right. It isn't in the 2nd edition, but is in the 1st.
> (I had mine packed away to take to a LaTeX Workshop that I'm
> giving today, so didn't check before replying.)
>
>
> I'd guess that the reason it was dropped is because you don't actually
> need the 'at' nor the number.
> Try this:
>
> \begin{align}
> u      &=0 & \quad\text{or}\quad  && u+4    &=0  & \quad\text{or} 
> \quad  && u-4    &=0 \\
> u      &=0 &&&                       u      &=-4  
> &&&                       u      &=4 \\
> \log x &=0 &&&                       \log x &=-4  
> &&&                       \log x &=4
> \end{align}
>
> The {align} environment counts the number of alignments actually
> used. But their treatment is the same: alternating right/left.

Ah!

\align is truly a great environment. I use it all the time, even  
instead of \displaymath. So, that's one more use.

Best regards
--schremmer