[Numpy-discussion] Bug in logaddexp2.reduce

Charles R Harris charlesr.harris@gmail....
Thu Apr 1 00:40:06 CDT 2010


On Wed, Mar 31, 2010 at 11:25 PM, <josef.pktd@gmail.com> wrote:

> On Thu, Apr 1, 2010 at 1:22 AM,  <josef.pktd@gmail.com> wrote:
> > On Thu, Apr 1, 2010 at 1:17 AM, Charles R Harris
> > <charlesr.harris@gmail.com> wrote:
> >>
> >>
> >> On Wed, Mar 31, 2010 at 6:08 PM, <josef.pktd@gmail.com> wrote:
> >>>
> >>> On Wed, Mar 31, 2010 at 7:37 PM, Warren Weckesser
> >>> <warren.weckesser@enthought.com> wrote:
> >>> > T J wrote:
> >>> >> On Wed, Mar 31, 2010 at 1:21 PM, Charles R Harris
> >>> >> <charlesr.harris@gmail.com> wrote:
> >>> >>
> >>> >>> Looks like roundoff error.
> >>> >>>
> >>> >>>
> >>> >>
> >>> >> So this is "expected" behavior?
> >>> >>
> >>> >> In [1]: np.logaddexp2(-1.5849625007211563, -53.584962500721154)
> >>> >> Out[1]: -1.5849625007211561
> >>> >>
> >>> >> In [2]: np.logaddexp2(-0.5849625007211563, -53.584962500721154)
> >>> >> Out[2]: nan
> >>> >>
> >>> >
> >>> > Is any able to reproduce this?  I don't get 'nan' in either 1.4.0 or
> >>> > 2.0.0.dev8313 (32 bit Mac OSX).  In an earlier email T J reported
> using
> >>> > 1.5.0.dev8106.
> >>>
> >>>
> >>>
> >>> >>> np.logaddexp2(-0.5849625007211563, -53.584962500721154)
> >>> nan
> >>> >>> np.logaddexp2(-1.5849625007211563, -53.584962500721154)
> >>> -1.5849625007211561
> >>>
> >>> >>> np.version.version
> >>> '1.4.0'
> >>>
> >>> WindowsXP 32
> >>>
> >>
> >> What compiler? Mingw?
> >
> > yes, mingw 3.4.5. , official binaries release 1.4.0 by David
>
> sse2 Pentium M
>
>
Can you try the exp2/log2 functions with the problem data and see if
something goes wrong?

Chuck
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