Type of the result of a log

[Jan Rychter]

In the following snippet of code:

                    #'(lambda (v1 v2)
                        (values (- (the double-float (log v1)) 
                                   (the double-float (log v2)))
                                0))

Is there a better way to tell CMUCL that I'm really sure that v1 and v2
are greater than 0.0d0 and are double-floats, so that the compiler
doesn't have to worry about the result of the logs becoming a COMPLEX?

I've tried things like:

  (declare (type (double-float 0.0d0) v1))

But that doesn't seem to work for me.

thanks,
--J.