(gitlab is uusable; i have to report here.)
ecl 21.2.1 gives:
(log 1/6319748715279270675921934218987893281199411530039296)
Debugger received error of type: DIVISION-BY-ZERO #<a DIVISION-BY-ZERO 0x7ff5afe6c540> Error flushed.
whereas other cl's (i testyed sbcl and ccl) give results like:
? (log 1/6319748715279270675921934218987893281199411530039296) -119.27552
I tested on amd64 (gentoo) and arm64 (debian and netbsd) with identical results. i did not have a musl box or other bsd to test on.
run with --no-trap-fpe, the result is #<single-float negative infinity>.
another example is:
(truncate (log 1/6319748715279270675921934218987893281199418867))
Debugger received error of type: ARITHMETIC-ERROR #<a ARITHMETIC-ERROR 0xffff8f688a40>
whereas this works:
(truncate (log 1/631974871527927067592193421898789328119941867))
-103 -0.27893066
which of course suggests that the issue is c's long double's precision.
it looks like ecl could use an mpq log function; https://github.com/linas/anant might work.
-JimC