You can use (library (scheme complex)) and (library (scheme inexact)) to determine the presence of complex and inexact numbers, which is why there are no features for them. 

John Cowan          http://vrici.lojban.org/~cowan        xxxxxx@ccil.org
Winter:  MIT, / Keio, INRIA, / Issue lots of Drafts.
So much more to understand! / Might simplicity return?
                (A "tanka", or extended haiku)