NB: More recent documentation for Dyalog APL is available at https://docs.dyalog.com/20.0/.

Domino;Quad Divide ⌹
Monadic Domino means

Matrix Inverse Of 

      mat
1 2
3 4
      ⌹ mat
¯2    1
 1.5 ¯0.5
Dyadic Domino means

Matrix Division By 

      5 6 ⌹ mat
¯4 4.5

Language Elements