[Bug math/2555] New: Incorrect return from float yn (2, 0X1.B12ED58FD5169P+1)

[Bug math/2555] New: Incorrect return from float yn (2, 0X1.B12ED58FD5169P+1)

[hjl at lucon dot org]

Failure: Test: yn (2, 0X1.B12ED58FD5169P+1) == -0X1.6541FD948522FP-58
Result:
 is:          5.96046447753906250000e-08   0x1.00000000000000000000p-24
 should be:  -4.84174579203368124914e-18  -0x1.6541fe00000000000000p-58
 difference:  5.96046447753906250000e-08   0x1.00000000000000000000p-24
 ulp       :  144115188075855872.0000
 max.ulp   :  0.0000

-- 
           Summary: Incorrect return from float yn (2, 0X1.B12ED58FD5169P+1)
           Product: glibc
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: math
        AssignedTo: aj at suse dot de
        ReportedBy: hjl at lucon dot org
                CC: glibc-bugs at sources dot redhat dot com
 GCC build triplet: x86_64-unknown-linux-gnu
  GCC host triplet: x86_64-unknown-linux-gnu
GCC target triplet: x86_64-unknown-linux-gnu


http://sourceware.org/bugzilla/show_bug.cgi?id=2555

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[Bug math/2555] Incorrect return from float yn (2, 0X1.B12ED58FD5169P+1)

[drepper at redhat dot com]

------- Additional Comments From drepper at redhat dot com  2006-04-23 17:53 -------
Suspended until somebody comes up with a patch.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |drepper at redhat dot com
             Status|NEW                         |SUSPENDED


http://sourceware.org/bugzilla/show_bug.cgi?id=2555

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[Bug math/2555] Incorrect return from float yn (2, 0X1.B12ED58FD5169P+1)

[zimmerma+gcc at loria dot fr]

https://sourceware.org/bugzilla/show_bug.cgi?id=2555

Paul Zimmermann <zimmerma+gcc at loria dot fr> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |zimmerma+gcc at loria dot fr

--- Comment #3 from Paul Zimmermann <zimmerma+gcc at loria dot fr> ---
for n=42, x=0x1.0c2d26p+9, rnd=RNDZ I get an error of -62183 ulps with glibc
2.18.90 (see http://www.loria.fr/~zimmerma/glibc/).

Paul

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[Bug math/2555] Incorrect return from float yn (2, 0X1.B12ED58FD5169P+1)

[jsm28 at gcc dot gnu.org]

http://sourceware.org/bugzilla/show_bug.cgi?id=2555

Joseph Myers <jsm28 at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|SUSPENDED                   |NEW
         AssignedTo|aj at suse dot de           |unassigned at sourceware
                   |                            |dot org

--- Comment #2 from Joseph Myers <jsm28 at gcc dot gnu.org> 2012-02-23 22:33:19 UTC ---
When that argument is rounded to float the correct result becomes
0x1.663952P-26.  But the result glibc gives is still 0X1P-24, so confirmed
(though I don't know how practical getting this very accurate is).

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