Hans Aberg
7. Juli 2015 18:23
On 7 Jul 2015, at 16:47, Wolfgang Schuster <schuster.wolfgang@gmail.com> wrote:



I get errors when using \MC - see example below.


The \NR before \stopmathcases is missing in all your examples.


OK. Though I know it, it is hard to get used to, coming from LaTeX.


But the spacing is wrong: too much between the two components. These are not cases, but aligned formulas: one might have a number of alignments, not just one. And I just happen to use left braces on them.


Take a look at my previous example where I changed the distance between both columns with the distance key.


I missed that. It fixes the spaces within the formula, but adds space between the two sets relative both TeX and AMS-LaTeX (which has about the same as TeX), cf. example below.

In AMS-LaTeX one can have more than one alignment, though when trying it between the “-“ and the “ω” in the second (right-most) set, it adds a lot of space, rather than just trying to align a compactly as possible. In ConTeXt, nothing happens with extra alignments; in TeX, there is an error.

So using \startmathcases is a workaround: trying to force it to do something it wasn’t intended for.
You can set the alignment for each column in a matrix with the align key.

\definemathmatrix
  [aligned]
  [n=2,
   align={right,left},
   distance=\spaceamount]

\starttext

\startformula
    J^j:
    \startaligned[left=\left\{,right=\right.]
        \NC ω^0 \NC ↦ 0 \NR
        \NC ω^j \NC ↦ 0 \NR
    \stopaligned
    \quad
    \startaligned[n=3,align={right,middle,left},left=\left\{,right=\right.]
        \NC ω^k \NC ↦ \NC  ω^l \NR
        \NC ω^l \NC ↦ \NC -ω^k \NR
    \stopaligned
\stopformula

\stoptext

Wolfgang