On Mon, 19 Jan 2009, Otared Kavian wrote:

> Hi everyone,
>
> This question is primarily intended for Aditya… but I guess other fellows on 
> the list can also help me solve the following alignment problem:
> Is it possible to have an alignment like the rsult of the following with 
> \startcases...\stopcases?
>
> \starttext
>
> \startformula
> \startmatrix[align={right,left,right},distance=3pt,left={\left\{}, 
> right={\right.}]
>  \NC -\Delta u + g(u) \NC{} = f \NC \quad\mbox{in } \Omega\NR
>  \NC \displaystyle {\partial u \over \partial {\bf n} } \NC{} = h(u) \NC 
> \quad\mbox{on } \partial\Omega   \NR
> \stopmatrix
> \stopformula
>
> \stoptext
>
> Actually I used to have such alignments with the following structure (in good 
> old plain TeX...):
>
> \starttext
>
> \startformula
> \cases{
> \eqalign{
> -\Delta u + g(u) &= f \cr
> \displaystyle {\partial u \over \partial {\bf n} } &= h(u) \cr
> } \quad \eqalign{
> &\hbox{in } \Omega \cr
> &\vphantom{{\partial u \over \partial {\bf n} }} \hbox{on } \partial\Omega 
> \cr
> }
> }
> \stopformula
>
> \stoptext
>
> (which gives approximately the same result as the first example above, but 
> clearly the math-alignment structure set up by Aditya and Hans is much more 
> elegant. (Although I prefer the vertical distance between the lines obtained 
> with my plain TeX structure: by the way is it possible to fine tune such 
> things in ConTeXt).
> So my question is: whether one can use \startcases ...\stopcases instead of 
> \startmatrix ... \stopmatrix in order to obtain the result of the plain TeX 
> example?

No, but there is not much difference between cases and matrix. Consider:

\definemathmatrix[alignedcase]
[align={right,left,right},distance=3pt,left={\left\{}, right={\right.},style=\displaystyle]
\starttext

\startformula
\startalignedcase
   \NC -\Delta u + g(u) \NC{} = f \NC \quad\mbox{in } \Omega\NR
   \NC {\partial u \over \partial {\bf n} } \NC{} = h(u) \NC \quad\mbox{on 
} \partial\Omega   \NR
\stopalignedcase
\stopformula

Aditya