Bug 2541 - Incorrect return from float erfc (0X1.FFA002P+2)
Summary: Incorrect return from float erfc (0X1.FFA002P+2)
Status: RESOLVED FIXED
Alias: None
Product: glibc
Classification: Unclassified
Component: math (show other bugs)
Version: unspecified
: P2 normal
Target Milestone: ---
Assignee: Joseph Myers
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2006-04-12 22:08 UTC by H.J. Lu
Modified: 2019-04-10 09:20 UTC (History)
2 users (show)

See Also:
Host: x86_64-unknown-linux-gnu
Target: x86_64-unknown-linux-gnu
Build: x86_64-unknown-linux-gnu
Last reconfirmed:
fweimer: security-

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Description H.J. Lu 2006-04-12 22:08:41 UTC 
Failure: Test: erfc (0X1.FFA002P+2) == 0X1.F466E4P-97
Result:
 is:          1.23359077991111300374e-29   0x1.f4676400000000000000p-97
 should be:   1.23358596508625203565e-29   0x1.f466e400000000000000p-97
 difference:  4.81482486096808963264e-35   0x1.00000000000000000000p-114
 ulp       :  64.0000
 max.ulp   :  0.0000
Maximal error of `erfc'
 is      : 64 ulp
 accepted: 0 ulp
Comment 1 Ulrich Drepper 2006-04-23 17:49:20 UTC 
Suspended until somebody comes up with a patch.
Comment 2 Joseph Myers 2012-02-19 18:07:22 UTC 
As I noted in http://sourceware.org/ml/libc-alpha/2012-02/msg00392.html this report is correct and the test should be added to the testsuite to document this 64ulp error.
Comment 3 Joseph Myers 2012-02-26 16:33:11 UTC 
Patch submitted: http://sourceware.org/ml/libc-alpha/2012-02/msg00640.html
Comment 4 Joseph Myers 2012-03-01 21:18:10 UTC 
Fixed by:

commit 7b1902cb3e64d340247638a8781770c3a4d850ce
Author: Joseph Myers <joseph@codesourcery.com>
Date:   Thu Mar 1 21:15:38 2012 +0000

    Improve erfc accuracy.