[RFC][PATCH 0/2] aarch64: Add optimized ASIMD versions of sinf/cosf

[Szabolcs Nagy]

On 23/06/17 11:49, Sekhar, Ashwin wrote:
> On Tue, 2017-06-13 at 12:07 +0100, Szabolcs Nagy wrote:
>>
>> - document the worst case ulp error and number of misrounded
>> cases: for single argument scalar functions you can easily test
>> all possible inputs in all rounding modes and that information
>> helps to decide if the algorithm is good enough.
>>
> I have a question on this. In order to calculate the ulp error for all
> possible inputs, I need to compare my implementation against another
> standard implementation.
> 
> Is it enough that I compare against the existing sinf implementation in
> glibc or is there any other standard implementation which I can use to
> compare against.
> 

no, don't compare it against sinf but against sin.

double precision has enough extra precision to be
a useful oracle for correct results.

(and you may want to compute ulp error in double
precision so you get more precision than just an
integer, but that can be a bit involved because
of special cases around overflow, nan, inf,..)