Re: Inaccurate results from numeric ln(), log(), exp() and pow() - Mailing list pgsql-hackers

Robert Haas <robertmhaas@gmail.com> writes:
> This patch, or something nearby, seems to have changed the number of
> significant figures produced by log() and maybe some of the other
> functions this patch touched.

Yeah, not surprising.

> It's certainly not obvious from the commit message that this change
> was expected.

That's on me as author of the commit message, I guess.  The rscale
in most of these functions is exactly the number of fraction digits
that will be emitted, and we changed the rules for computing it.
Not by much, in most cases.  I don't think we should be too worried
about being bug-compatible with the old behavior.
        regards, tom lane