standards/83845: [libm] [patch] add log2() and log2f() support for libm

[David Schultz]

On Thu, Dec 31, 2009, Mark Diekhans wrote:
>  How about integrating the C99 math functions into libm?  This PR has been pending
>  for four years.  NetBSD already has them:
>  
>     http://cvsweb.netbsd.org/bsdweb.cgi/src/lib/libm/src/
>  
>  Makes it hard to port software and to advocate for FreeBSD being a
>  standards-compliant platform.

IIRC, the proposed implementation is a somewhat simplistic port
of log(), and it generates rather inaccurate results.  In particular,
you might as well just #define log2(x) (log(x)/log(2)).
The hope is that we'll get a real implementation of this function,
rather than putting in a kludge so we can pretend we don't need one.
I'm not going to have time for it on the near future myself, but
Steve Kargl has been working on better math library functions for a
while, and hopefully he will have some stuff ready soon.