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From: Paul Zimmermann <Paul.Zimmermann@inria.fr>
To: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Cc: libc-alpha@sourceware.org, joseph@codesourcery.com
Subject: Re: [PATCH] Fix the inaccuracy of j0f (BZ 14469) and y0f (BZ 14471) [v2]
Date: Mon, 25 Jan 2021 10:59:14 +0100	[thread overview]
Message-ID: <mw35ypl4lp.fsf@oignon.loria.fr> (raw)
In-Reply-To: <f8944d2d-f0c5-c6d1-85c1-397ea9599426@linaro.org> (message from Adhemerval Zanella on Fri, 22 Jan 2021 11:37:54 -0300)

       Dear Adhemerval,

> So if I understand correctly, you patch increase the ulps for non-default
> rounding for this specific inputs? If it were the case, could be fix it
> as well? 

I guess the previous code already had an error > 9 ulps on this specific
input:

Failure: Test: j0_downward (0x3.17bcfcp+4)
Result:
 is:          1.1670220923447945e-04   0x1.e97c0b0296dc8p-14
 should be:   1.1670220923447976e-04   0x1.e97c0b0296ddfp-14
 difference:  3.1170812458958252e-19   0x1.7000000000000p-62
 ulp       :  23.0000
 max.ulp   :  2.0000

However on my machine I have an error of only 9 ulps for that input.
Maybe your machine doesn't have fma? Maybe I should develop my code
on a machine without fma, assuming the errors will be smaller with fma.

Paul

  parent reply	other threads:[~2021-01-25  9:59 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-22 10:43 Paul Zimmermann
2021-01-22 13:04 ` Adhemerval Zanella
2021-01-22 14:23   ` Paul Zimmermann
2021-01-22 14:37     ` Adhemerval Zanella
2021-01-22 15:06       ` Joseph Myers
2021-01-25  9:59       ` Paul Zimmermann [this message]
2021-01-25 13:01         ` Adhemerval Zanella

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