Fabrice Couvreur schrieb am 13.05.2019 um 22:45:
> Hi,
> Not having too many ideas, I did this: is there not a more elegant way ?
\definemathmatrix [pmatrix] [matrix:parentheses] [simplecommand=MATRIX]

\starttext

\startformula
   \startmathalignment
   \NC P \times M = P \NC \iff \MATRIX{x,y} \times 
\MATRIX{0.22,0.78;0.53,0.47} = \MATRIX{x,y} \NR
   \NC                \NC \iff
     \startmathcases
     \NC 0.22x + 0.53y = x \NR
     \NC 0.78x + 0.47y = y \NR
     \stopmathcases
   \NR
   \NC                \NC \iff 0.78x - 0.53y = 0 \NR
   \NC                \NC \iff   78x -   53y = 0 \NR
   \stopmathalignment
\stopformula

\stoptext

Wolfgang