¨) is a primitive monadic operator which applies its operand to each element of the arguments, and returns an array whose elements are the results. If two arguments are given, their elements are matched using conformability rules.
Each is defined only in nested APLs. Some flat APLs obtain analogous functionality by using an Under operator with close composition along with the rank-0 function Disclose (or Unbox). In SHARP APL this is written
f¨>. In J it is