f may be any dyadic function.  X and Y may be any arrays whose corresponding items (after scalar extension) are appropriate to function f when applied separately.

The derived function is applied separately to each pair of corresponding elements of X and Y.  If X or Y is a scalar or single-element array, it will be extended to conform with the other argument.  The derived function need not produce an explicit result.  If a result is returned, R has the same shape as Y (after possible scalar extension) whose elements are the items produced by the application of the derived function to the corresponding items of X and Y.

If X or Y is empty, the operand function is applied once between the prototypes of X and Y to determine the prototype of R.

      +G←(1 (2 3))(4 (5 6))(8 9)10
   1  2 3   4  5 6   8 9  10
      1⌽¨G
  2 3  1   5 6  4  9 8  10
 
      1⌽¨¨G
 1  3 2   4  6 5   8 9  10
 
      1⌽¨¨¨G
 1  2 3   4  5 6   8 9  10
 
      1 2 3 4↑¨G
 1  4  5 6   8 9 0  10 0 0 0
 
      'ABC',¨'XYZ'
 AX  BY  CZ