Re: \begin{cases} .. \end{cases} in ConTeXt

[Brooks Moses <bmoses@stanford.edu>]

At 04:42 PM 9/12/2005, you wrote:
>I have tried with:
>
>\startcases
>.. \stopcases
>
>and many others variations but I have got only errors.
>Any hint?

Much like the bmatrix environment, the cases environment is an AMSmath 
package feature, and ConTeXt at present has very few of the direct 
equivalents to those implemented.  You'll need to make this one up with a 
Plain TeX \matrix, as well.  (The TeXbook is a pretty good reference for this.)

Something like this should work, to recreate the example from page 8 of the 
AMSmath manual:

   P_{r-j} =
   \left\lbrace
     \matrix{
        0                 \hfill& \text{if $r-j$ is odd}   \hfill\cr
        r!(-1)^{(r-j)/2}  \hfill& \text{if $r-j$ is even}  \hfill\cr
     }
   \right.

The \left\lbrace and \right. create the properly expanded brace at the 
left, the \matrix handles putting things in the right places, the \hfills 
make each of the columns left-aligned, and the \text{} commands (which _do_ 
exist in ConTeXt, unlike in Plain TeX) typeset their arguments as text 
rather than math.

- Brooks