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From: Paul Zimmermann <Paul.Zimmermann@inria.fr>
To: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
Cc: mwelinder@gmail.com, libc-alpha@sourceware.org,
	adhemerval.zanella@linaro.org
Subject: Re: Man page issues: logb, significand, cbrt, log2, log10, exp10
Date: Tue, 05 Mar 2024 09:14:56 +0100	[thread overview]
Message-ID: <p9u0le6xw0vz.fsf@coriandre.loria.fr> (raw)
In-Reply-To: <PAWPR08MB8982BDA236461B6890D6F88583232@PAWPR08MB8982.eurprd08.prod.outlook.com> (message from Wilco Dijkstra on Mon, 4 Mar 2024 15:29:00 +0000)

       Hi Wilco,

> The worst case error of MUSL is 4.14 ULP vs 2.01 ULP of the old GLIBC exp10 [1].
> 
> And the new exp10 in GLIBC is 0.513 ULP [2].

yes the new exp10 is more accurate, nice work!

> As I pointed out in the PR, it would be reasonable for compilers to convert
> pow (10, x) into exp10 (x) when it is known there is a good implementation
> available - in GLIBC, exp10 is both faster and slightly more accurate than pow.

ok at compile time, but there should be a way to disable this optimization,
for example if you want to compare pow(10,x) and exp10(x). (At run time
such a conversion would slow down the critical path of pow.)

Paul

  reply	other threads:[~2024-03-05  8:14 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-03-04 15:29 Wilco Dijkstra
2024-03-05  8:14 ` Paul Zimmermann [this message]
     [not found] <CANv4PNkVv_0eLgiSP3L_KfC-eZJaVLZ5AP1AGfD0GNrR5M4Hrg@mail.gmail.com>
     [not found] ` <ZeEnJB96mMC5bfBz@debian>
     [not found]   ` <CANv4PNmMpiwfv5acr7U6VEVe7PE_AMTzkkpNoNN9jrtVzk_93Q@mail.gmail.com>
2024-03-02 21:54     ` Alejandro Colomar
2024-03-03  2:02       ` Morten Welinder
2024-03-03  2:21         ` Alejandro Colomar
2024-03-03 11:46           ` Vincent Lefevre
2024-03-03 12:21             ` Alejandro Colomar
2024-03-03 22:26               ` Morten Welinder
2024-03-04 12:17         ` Adhemerval Zanella Netto

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