[Bug math/706] pow() produces inaccurate results for base ~ 1.0, and large integer exponent on 32-bit x86

["vincent-srcware at vinc17 dot net" <sourceware-bugzilla at sourceware dot org>]

http://sourceware.org/bugzilla/show_bug.cgi?id=706

Vincent LefÃvre <vincent-srcware at vinc17 dot net> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|pow() produces inaccurate   |pow() produces inaccurate
                   |results for base ~ 1.0, and |results for base ~ 1.0, and
                   |large exponent on 32-bit    |large integer exponent on
                   |x86                         |32-bit x86

--- Comment #14 from Vincent LefÃvre <vincent-srcware at vinc17 dot net> 2012-02-28 16:36:13 UTC ---
I've done some tests, and it seems that pow(x,y) for large y is inaccurate only
when y is an integer. So, if I understand correctly, an iterative algorithm is
used for integers y, and a log-exp algorithm (which seems accurate enough on
the few values I've tested) is used for other values. So, a possible easy fix
would be to always use the log-exp algorithm, possibly except for small
integers y.

Note: I've updated the bug summary following this observation (large exponent â
large integer exponent).

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