-ansi flag effects

You may have read my May 26th message (made at 14:43, called Specifying
include link flags).  In it I described problems I was having getting certain
(logb, scalbn, log1p) math functions to work.  I have determined that this
problem occurs only when I use the -ansi flag.  If -ansi is used, the
function protypes aren't included and linking produces innaccurate
results.  If -ansi isn't used then there are no problems.  Is there
documentation (I have come across some partial documentation, but nothing
exhaustive) on which functions the -ansi flag effects?

Thanks,
Andrew Binkley