Bug 2540 - Incorrect return from float acosh (0X1.01FB0B7471C13P+0)
Summary: Incorrect return from float acosh (0X1.01FB0B7471C13P+0)
Status: RESOLVED DUPLICATE of bug 14759
Alias: None
Product: glibc
Classification: Unclassified
Component: math (show other bugs)
Version: unspecified
: P2 normal
Target Milestone: ---
Assignee: Not yet assigned to anyone
Depends on:
Reported: 2006-04-12 22:05 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 22:05:35 UTC
Failure: Test: acosh (0X1.01FB0B7471C13P+0) == 0X1.FD303BDCD51D2P-4
 is:          1.24313831329345703125e-01   0x1.fd308000000000000000p-4
 should be:   1.24313578009605407715e-01   0x1.fd303c00000000000000p-4
 difference:  2.53319740295410156250e-07   0x1.10000000000000000000p-22
 ulp       :  34.0000
 max.ulp   :  0.0000
Comment 1 Ulrich Drepper 2006-04-23 17:48:55 UTC
Suspended until somebody comes up with a patch.
Comment 2 Joseph Myers 2012-02-19 18:05:29 UTC
When that argument is rounded to float it's 0X1.01FB0CP+0 and the correctly rounded result is 0X1.FD3082P-4.  So this is a 1ulp error, not 34ulp.  (Since there are no testcases in the testsuite expecting any error from acoshf, we should still add that actual float value to the testsuite.)
Comment 3 Joseph Myers 2012-10-24 12:44:26 UTC
Collecting all reports of few-ulps errors together in one meta-bug.

*** This bug has been marked as a duplicate of bug 14759 ***