Log requires floating point?

Does log need to be computed using floating-point representation? This excludes the larger part of bignums.

This is a test:

(define x (expt 10 2480))
(log x)

If the implementation wants to answer (log x) with the correct number, the logarithm must be calculated without the floating-point C library log function, since the number is far too large to fit in current days 64-bit doubles.

System result
Bigloo -inf.0
Biwa +inf.0
Chez 5710.411030625233
Chibi +inf.0
Chicken +inf.0
Cyclone +inf.0
Foment +inf.0
Gambit 5710.411030625233
Gauche 5710.411030625233
Guile 5710.411030625233
Kawa +inf.0
LIPS +inf.0
Loko +inf.0
MIT +inf.0
Racket 5710.411030625233
Sagittarius 5710.411030625233
Scheme 9 5710.41103062521399
STklos +inf.0
Tinyscheme +inf.0
Unsyntax +inf.0
Ypsilon 5710.411030625233
ABCL error
CCL 5710.411
Clisp 5710.411
CMUCL 5710.411
ECL 5710.411
SBCL 5710.411
Emacs Lisp 1.0e+INF

Another experiment:

(log 1/6319748715279270675921934218987893281199411530039296)

Should return -119.27551918982401. (This was posted to the ECL mailing list on 2022-Jul-03 -- ECL does not compute the value, and complains about the user requesting log of zero).

All others return the correct result; Bigloo and Scheme9 need the rational to be described as division, not as rational type.

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