Dear List, 

I have a trouble with this formula, because, I would like to have c + d also in the matrix, but it is not working. 

\starttext 
\startformula
\startmathmatrix[fences=doublebar]
 \pmatrix 
  { a  + b\NR}  
   { c  + d \NR}
\stopmathmatrix
\stopformula
\stoptext 

 

And another question too: 


I would like to need the command \parallel, instead of the fences, how can I make them big?  



Many thanks 


Uschi