⍤ — Atop / RankWith function operand g, f⍤g Y is f(g Y) and X f⍤g Y is f(X g Y).
2 -⍤+ 3 ⍝ ¯5
With numeric operand R, f⍤R applies to trailing cells of rank R. Frames use leading agreement; results assemble with fill.
(+/⍤1)2 3⍴⍳6 ⍝ 6 15
R |
Monad rank | Dyad left/right ranks |
|---|---|---|
r |
r |
r r |
q r |
r |
q r |
p q r |
p |
q r |
Negative ranks count back from argument rank; excessive ranks clamp. Empty frames call the operand on prototype cells.