On 1 April 2010 01:40, Charles R Harris charlesr.harris@gmail.com wrote:
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?
Works fine for me.
If it helps clarify things, the difference between the two problem input values is exactly 53 (and that's what logaddexp2 does an exp2 of); so I can provide a simpler example:
In [23]: np.logaddexp2(0, -53) Out[23]: nan
Of course, for me it fails in both orders.
Anne