standards/83845: [ patch ] add log2() and log2f() support for
libm
Roman Bogorodskiy
bogorodskiy at gmail.com
Sat Jul 23 04:50:20 GMT 2005
The following reply was made to PR standards/83845; it has been noted by GNATS.
From: Roman Bogorodskiy <bogorodskiy at gmail.com>
To: "Steven G. Kargl" <kargls at comcast.net>
Cc: bug-followup at FreeBSD.org
Subject: Re: standards/83845: [ patch ] add log2() and log2f() support for libm
Date: Sat, 23 Jul 2005 08:50:13 +0400
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Steven wrote:
> See standards/82654.
>=20
> I have implementations for several C99 long double math functions,
> and in the process I implemented log2 and logf. I also wrote or
That's really great, since our libmath is a bit outdated and nobody
seems to care about that.
> edited the man pages. IMHO, for log2[fl], we want to use frexp[fl]
> to break x into x =3D f * 2**n where f is in the range [0.5,1). We
> then have log2(x) =3D n + log2(f). We can now either evaluate log2(f)
> as log(f)/log(2) or directly use a polynomial approximation.
That looks reasonable. Actually, I don't care which implementation will
be used, your or mine or some another, I'd just like to have it
implemented. But looking at the batch of open standarts PRs I think we
have no chance to get it committed in the near future. :(
Roman Bogorodskiy
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