"Return the logarithm of NUMBER in the base BASE, which defaults to e."
(if base-p
(cond
- ((zerop base) base) ; ANSI spec
+ ((zerop base) 0f0) ; FIXME: type
((and (typep number '(integer (0) *))
(typep base '(integer (0) *)))
(coerce (/ (log2 number) (log2 base)) 'single-float))