From: Paul Zimmermann <Paul.Zimmermann@inria.fr>
To: Szabolcs Nagy <szabolcs.nagy@arm.com>
Cc: Wilco.Dijkstra@arm.com, libc-alpha@sourceware.org
Subject: Re: [PATCH 1/5] Remove slow paths from asin
Date: Mon, 04 Jan 2021 18:41:13 +0100 [thread overview]
Message-ID: <mwim8czjk6.fsf@tomate.loria.fr> (raw)
In-Reply-To: <20210104170620.GJ2379@arm.com> (message from Szabolcs Nagy on Mon, 4 Jan 2021 17:06:21 +0000)
Dear Szabolcs,
> previously it was noted that there are incorrectly rounded
> cases in asin that were not caught by those checks:
> https://sourceware.org/legacy-ml/libc-alpha/2020-01/msg00574.html
the patch you mention (commit f67f9c9) was already entitled
"ieee754: Remove slow paths from asin and acos". This was confusing.
I believe it did only remove the "very slow" paths.
> in my experience the original code is fairly conservative
> so in most cases i'd expect the Max ULP to be an upper
> bound with significant margin, not the actual worst case
> error.
here are the claimed bounds and the maximal errors I found so far after
applying Wilco's patches (rounded up to 3 digits):
claimed found so far
acos 0.52 0.523
asin 0.523 0.516
atan 0.56 0.523
tan 0.62 0.612
atan2 0.56 0.524
Paul
next prev parent reply other threads:[~2021-01-04 17:41 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-04 12:11 [PATCH 0/5] Remove remaining slow paths from math functions Wilco Dijkstra
2021-01-04 12:15 ` [PATCH 1/5] Remove slow paths from asin Wilco Dijkstra
2021-01-04 16:25 ` Paul Zimmermann
2021-01-04 17:06 ` Szabolcs Nagy
2021-01-04 17:41 ` Paul Zimmermann [this message]
2021-01-07 19:36 ` Wilco Dijkstra
2021-01-08 10:29 ` Paul Zimmermann
2021-01-07 19:23 ` [PATCH v2 1/5] Remove remaining slow paths from asin and acos Wilco Dijkstra
2021-01-04 12:17 ` [PATCH 2/5] Remove slow paths in tan Wilco Dijkstra
2021-01-04 16:36 ` Paul Zimmermann
2021-01-07 19:25 ` [PATCH v2 " Wilco Dijkstra
2021-01-04 12:19 ` [PATCH 3/5] Remove slow paths from atan Wilco Dijkstra
2021-01-04 16:43 ` Paul Zimmermann
2021-01-07 19:26 ` [PATCH v2 " Wilco Dijkstra
2021-01-04 12:21 ` [PATCH 4/5] Remove slow paths from atan2 Wilco Dijkstra
2021-01-04 16:49 ` Paul Zimmermann
2021-01-07 19:28 ` [PATCH v2 " Wilco Dijkstra
2021-01-04 12:25 ` [PATCH 5/5] Remove mpa files Wilco Dijkstra
2021-01-07 20:12 ` [PATCH v2 " Wilco Dijkstra
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