Date: Sat, 23 Jul 2005 02:10:19 GMT From: "Steven G. Kargl" <kargls@comcast.net> To: freebsd-standards@FreeBSD.org Subject: Re: standards/83845: [ patch ] add log2() and log2f() support for libm Message-ID: <200507230210.j6N2AJ2S062457@freefall.freebsd.org>
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The following reply was made to PR standards/83845; it has been noted by GNATS. From: "Steven G. Kargl" <kargls@comcast.net> To: bug-followup@FreeBSD.org, bogorodskiy@gmail.com Cc: Subject: Re: standards/83845: [ patch ] add log2() and log2f() support for libm Date: Fri, 22 Jul 2005 19:02:15 -0700 See standards/82654. I have implementations for several C99 long double math functions, and in the process I implemented log2 and logf. I also wrote or edited the man pages. IMHO, for log2[fl], we want to use frexp[fl] to break x into x = f * 2**n where f is in the range [0.5,1). We then have log2(x) = n + log2(f). We can now either evaluate log2(f) as log(f)/log(2) or directly use a polynomial approximation. -- steve
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