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Re: [PATCH] Update sparc ULPs.
On Sun, 18 Nov 2012, David Miller wrote:
> I've done some investigation meanwhile and we end up down in
> atanl(), via atan2l().
>
> atan2l: x[-2.083218e+306L] y[1.755781e+174L]
>
> atanl: x[-7.672687e+306L]
>
> And the atanl() is what generates the spurious underflow.
I don't know if this is an "atan of large argument" issue, but I see we
don't have any direct tests in the testsuite for atan / atan2 of large
finite arguments at all. Maybe we should have tests of atan (+/-
max_value) and atan2 (+/- max_value, +/-min_value) - expected results all
being +/- M_PI_2l. And for that matter, atan2 (+/- min_value, max_value),
expected results +/- M_PIl, to verify that that doesn't produce any
spurious underflows either (as it would for a naive conversion from atan2
to atan).
--
Joseph S. Myers
joseph@codesourcery.com