[R6RS] Arithmetic loose ends

[William D Clinger]

Mike wrote:
> - Months ago, I added `integer-sqrt', but I seem to remember we also
>   agreed to put in `integer-length'.  However, I'm not sure. Right?

We added exact-integer-sqrt.  Regardless of whether we
agreed to add exact-integer-length, I think we should
do it.

> - Some people suggested extending `log' to accept an optional base
>   argument:
>
> http://srfi.schemers.org/srfi-77/mail-archive/msg00439.html
>
>   This makes sense to me.  Any reason why we shouldn't?

No.  That would be a welcome extension.  For the same
reasons we discussed when unifying the argument order
for the various operations on bytes, however, I think
the order of arguments should be

    (log z)    ; natural logarithm
    (log z b)  ; logarithm base b (b > 0)

Will