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Date:      Wed, 08 May 2019 20:16:50 +0000
From:      bugzilla-noreply@freebsd.org
To:        numerics@FreeBSD.org
Subject:   [Bug 237800] pow(3) returns inaccurate results
Message-ID:  <bug-237800-18636-R8M7CtVYjJ@https.bugs.freebsd.org/bugzilla/>
In-Reply-To: <bug-237800-18636@https.bugs.freebsd.org/bugzilla/>
References:  <bug-237800-18636@https.bugs.freebsd.org/bugzilla/>

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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D237800

--- Comment #4 from sgk@troutmask.apl.washington.edu ---
When you say you get the correct value on Linux, are you using clang 8.0.0 =
on
Linux or some version of gcc?  gcc will constant fold pow(10,29) using MPFR=
.=20
Clang will generated a call to pow() in libm.

In any event, the library is computing pow(10,29) as exp(29*log(10))
where special polynomial approximations are being used.  With a ULP
of 0.51, I suppose reading Goldberg's paper is merited.

--=20
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