[Bug math/3407] New: powf gives inaccurate results on x86_64

[Bug math/3407] New: powf gives inaccurate results on x86_64

[myles at peakstreaminc dot com]

The attached sample code gives inaccurate results on x86_64 compared to 32 bit 
where it works.

gcc version 3.4.5 20051201 (Red Hat 3.4.5-2)
glibc-2.3.4-2.19

powf results fractional error is larger than 1 part in 1 million.

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           Summary: powf gives inaccurate results on x86_64
           Product: glibc
           Version: 2.3.4
            Status: NEW
          Severity: normal
          Priority: P2
         Component: math
        AssignedTo: aj at suse dot de
        ReportedBy: myles at peakstreaminc dot com
                CC: glibc-bugs at sources dot redhat dot com
  GCC host triplet: 2.6.9-34.ELsmp x86_64


http://sourceware.org/bugzilla/show_bug.cgi?id=3407

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[Bug math/3407] powf gives inaccurate results on x86_64

[myles at peakstreaminc dot com]

------- Additional Comments From myles at peakstreaminc dot com  2006-10-22 00:44 -------
Created an attachment (id=1384)
 --> (http://sourceware.org/bugzilla/attachment.cgi?id=1384&action=view)
test program

OUTPUT on x86_64 system
-----------------------
x is 0.843334257602691650390625
y is -370
 pow(x,y)  is 2399359442378151177461170176
 powf(x,y) is 2399362098709297791636602880
 fractional error 1.1071e-06


------------------------------------


Output on 32 bit system (CORRECT!)
----------------------------------

x is 0.843334257602691650390625
y is -370
 pow(x,y)  is 2399359442378151177461170176
 powf(x,y) is 2399359442378151177461170176
 fractional error 0


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http://sourceware.org/bugzilla/show_bug.cgi?id=3407

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[Bug math/3407] powf gives inaccurate results on x86_64

[vincent+libc at vinc17 dot org]

------- Additional Comments From vincent+libc at vinc17 dot org  2009-09-24 08:12 -------
Bug 1161 is also about powf inaccuracy on x86_64. Marking as dup.

*** This bug has been marked as a duplicate of 1161 ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |DUPLICATE


http://sourceware.org/bugzilla/show_bug.cgi?id=3407

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