Y must be a numeric array. R is numeric.  R is the natural (or Napierian) logarithm of Y whose base is the mathematical constant e=2.71828....

Example

      ⍟1 2
0 0.6931471806
 
      ⍟2 2⍴0j1 1j2 2j3 3j4
0.000000000J1.570796327  0.8047189562J1.107148718
1.282474679J0.9827937232 1.6094379120J0.927295218