From: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
To: Joseph Myers <joseph@codesourcery.com>,
Steve Ellcey <sellcey@cavium.com>
Cc: "Zack Weinberg" <zackw@panix.com>,
"Ondřej Bílka" <neleai@seznam.cz>,
"Siddhesh Poyarekar" <siddhesh@gotplt.org>,
"libc-alpha@sourceware.org" <libc-alpha@sourceware.org>,
nd <nd@arm.com>
Subject: Re: [PATCH 2/6] Remove slow paths from sin/cos
Date: Mon, 12 Mar 2018 15:36:00 -0000 [thread overview]
Message-ID: <DB6PR0801MB2053FB9617BC2B77635BF98183D30@DB6PR0801MB2053.eurprd08.prod.outlook.com> (raw)
In-Reply-To: <alpine.DEB.2.20.1803100049290.28686@digraph.polyomino.org.uk>
Joseph Myers wrote:
> Yes. A floating-point number represents a particular real number, not an
> interval, so all the usual accuracy goals (of results within a few ulps of
> the correct answer) apply for large inputs (but performance is not a
> concern for those inputs). Only for IBM long double is this relaxed, to
> treat values not representable in 106 mantissa bits as if they do
> represent intervals.
Though these patches keep the ULP accuracy across the full range as is,
we could agree on higher ULP errors for large/huge range reduction cases
in the future. The main complexity is for certain rare inputs which happen to
be extremely close to an integer multiple of PI/2, and those few cases mean
you need significant extra work to guarantee 0.5 ULP error bound on range
reduction.
Wilco
next prev parent reply other threads:[~2018-03-12 15:36 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-09 15:46 Wilco Dijkstra
2018-03-09 16:17 ` Siddhesh Poyarekar
2018-03-09 18:19 ` Ondřej Bílka
2018-03-09 18:52 ` Zack Weinberg
2018-03-09 23:05 ` Steve Ellcey
2018-03-10 0:52 ` Joseph Myers
2018-03-12 15:36 ` Wilco Dijkstra [this message]
2018-03-12 15:46 ` Zack Weinberg
2018-03-12 16:10 ` Joseph Myers
2018-03-12 21:13 ` Wilco Dijkstra
2018-03-09 19:06 ` Wilco Dijkstra
2018-03-09 19:31 ` Siddhesh Poyarekar
2018-03-12 18:09 ` Wilco Dijkstra
2018-03-13 8:53 ` Siddhesh Poyarekar
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