exponent-of function



The source code documentation for exponent-of says 

;; Basically computes log of m base b. Except if m is not a power of b, we return nil.

But

 (%i2) exp_of(k,m) := ?exponent\-of(k,m)$

 (%i3) exp_of(6,2);
 (%o3) 1

 (%i4) exp_of(2,-2);
 (%o4) 1

Is exponent-of broken and the source code comment correct?

--Barton