[texhax] Exempting an equation from alignment

[Soeren D. Schulze]

E. Krishnan wrote:
> On Sat, 4 Aug 2007, Soeren D. Schulze wrote:
> 
>> I need to format something like this (whitespace-formatted here):
>>
>>   x (x + 1) = 0
>> => x_1 = 0
>>       x + 1 = 0
>> => x_2 = -1
>>
>> This is quite a stupid example, but the first and the third line are
>> supposed to be aligned (equal signs below each other), whereas the
>> second and the fourth line are not supposed to influence the alignment,
> 
> 
> Will this do?
> 
> \(\setlength{\arraycolsep}{0pt}
>    \begin{array}{rr@{\;}l}
>                  & x(x + 1) & = 0\\
>      \Rightarrow & \multicolumn{2}{l}{x_1=0}\\
>                  & x+1      & = 0\\
>      \Rightarrow & \multicolumn{2}{l}{x_2=-1}
>    \end{array}\)

The `array' command is exactly what I was looking for, thank you
(especially for the quick reply).

Is there any reason to prefer either `array' or `align' in cases where
they would both do the job?


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