[Mesa-dev] [PATCH] Improve ONE_DIV_LN2 and M_PI constants

Matt Turner mattst88 at gmail.com
Wed Dec 1 15:31:07 PST 2010


On Wed, Dec 1, 2010 at 11:24 PM, Ian Romanick <idr at freedesktop.org> wrote:
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> On 12/01/2010 01:40 PM, Matt Turner wrote:
>> 1/ln(2) is equivalent to log2(e), so define it as such.
>>
>> log2(e) = ln(e)/ln(2) = 1/ln(2)
>>
>> M_PI is updated to add some precision (value found in my math.h header).
>
> I wish I had noticed this when I added M_LOG2E.  It seems better to
> replace the single use of ONE_DIV_LN2 (in prog_statevars.c) with M_LOG2E.

Yeah, I wondered if that would be better, but wasn't sure if 1/ln(2)
in that particular case contained some semantic meaning.

Should I send a new patch to s/ONE_DIV_LN2/M_LOG2E/ and a separate one
for the M_PI definition?


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