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Re: acos / asin accuracy
- From: "Carlos O'Donell" <carlos at systemhalted dot org>
- To: "Henri Verbeet" <hverbeet at gmail dot com>
- Cc: libc-help at sourceware dot org
- Date: Sun, 21 Sep 2008 16:28:29 -0400
- Subject: Re: acos / asin accuracy
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- References: <d658b69e0809210804t75951f79qc6d258f9f662916b@mail.gmail.com> <119aab440809210935j3f67cbbevaad4696180d2d66b@mail.gmail.com> <d658b69e0809211009j6364c734u5c33018dbb7e7abb@mail.gmail.com>
On Sun, Sep 21, 2008 at 1:09 PM, Henri Verbeet <hverbeet@gmail.com> wrote:
>> Do you have a patch, with before and after results, including the
>> results of running the glibc math testsuite?
>>
> No, but I could write one if needed, just need to find the time. On
> the other hand, it's easy enough to see that for a value like
> 0x3feffffffff00000 x*x gets rounded to 0x3fefffffffe00000, which after
> subtracting from 1 becomes 0x3df0000000000000, while (1-x)(1+x)
> correctly gives 0x3deffffffff80000.
Please file an issue. Remember that we are all volunteers :-)
The more you make everyone care about your issue the more likely it is
for someone to fix.
Cheers,
Carlos.