Re: What is equivalent of latex math aligned in ConTeXt?

[Aditya Mahajan <adityam@umich.edu>]

On Mon, 11 May 2009, Xan wrote:

> Hi,
>
> I read the document "Using \startalign and friends" of Aditya (that it's 
> good) and I can't find anything under ams aligned. Is this an equivalent in 
> ConText?

Strictly speaking, none. You can fake aligned and gathered with matrices.

> For example, what is the equivalent of:
>
> \begin{equation*}
> \left.\begin{aligned}
> & 2^2 | n_0\\
> & 4^2 | n_0 + 2 \Rightarrow (2^2)^2 | n_0 +2 \Rightarrow 2^2 | n_0 +2 \text{ 
> ya que } 2^2 | (2^2)^2
> \end{aligned}\right\} \Rightarrow 2^2 | (n_0 + 2 - n_0) \Rightarrow 2^2 | 2
> \end{equation*}
>
> in ConTeXt?
>
> I tried something like:
>
> \startformula
> \startmathalignment
> \NC \startaligned
> \NC \lambda_{0, \lvert k - s \rvert} (n) \NC < f(n) \NR
> \NC \text{ per a $n$ suficientment gran } \NC \NR
> \stopaligned \NC  \iff
> \startaligned
> \NC \lambda_{s, k} (n) \NC < f(n) \NR
> \NC \text{ per a $n$ suficientment gran } \NC \NR
> \stopaligned \NR[+]
> \NC \lambda_{s, k} (n) < f(n) \text{ per a $n$ suficientment gran } \NC \iff 
> \lambda_{0, \lvert k - s \rvert} (n) < f(n) + C \text{ per a $n$ 
> suficientment gran }  \NR[+]
> \stopmathalignment
> \stopformula
>
> but " Undefined control sequence" appears to me.

Of course. The command \startaligned is not defined. Here is one way to do 
this.

\definemathmatrix[rightbrace]
 		[align=left,
 		left={\left.},
 		right={\right\}},
 		style=\displaystyle]

\starttext
\startformula
   \startrightbrace
     \NC 2^2 | n_0 \NR
     \NC 4^2 | n_0 + 2
         \Rightarrow (2^2)^2 | n_0 +2
         \Rightarrow 2^2 | n_0 +2 \text{ ya que } 2^2 | (2^2)^2
         \NR
   \stoprightbrace
   \Rightarrow 2^2 | 2
\stopformula
\stoptext


I would also use \implies instead of \Rightarrow (slightly different 
spacing).

Aditya
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