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Subject: Re: [PATCH] Add sinh(tanh(x)) and cosh(tanh(x)) rules
To: Giuliano Augusto Faulin Belinassi <giuliano.belinassi@usp.br>
Cc: GCC Patches <gcc-patches@gcc.gnu.org>, Paul Koning <paulkoning@comcast.net>
References: <CAEFO=4C+BLJYGHNwuCbjdeY2Xj5KJkBeRRCKmSxqTUqwVokkag@mail.gmail.com> <1a9f1bf8-cb6a-41e3-e13f-d7743bc16dcb@redhat.com> <CAEFO=4BGUTJ0d58Z-MP6yPOOm+DS6gVL7-C0Bg_H0KiVA8ZF7Q@mail.gmail.com>
From: Jeff Law <law@redhat.com>
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Date: Tue, 16 Oct 2018 21:16:00 -0000
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On 10/12/18 8:36 AM, Giuliano Augusto Faulin Belinassi wrote:
> Hello.
>     I don't think there is a need for overflow handling here because
> the argument is bound by the argument of the sqrt function :-)
Yea, I guess you're right.  The domain of arctanh is -1 to 1, so I guess
we're safe there.  Except for the case where  the input is -1 or 1 in
which case I think you just set the output to +- INF as appropriate.

Hmm, do we have problems as we get close to -1 or 1 where the outputs of
the two forms might diverge?

Jeff