[Numpy-discussion] [Bug] important bug in method sum

humufr@yah... humufr@yah...
Tue Feb 5 13:58:40 CST 2008


				Hello,

when doing some test I saw a very important bug in numpy (at least on the svn 
version and 1.0.3 (ubuntu package)).

I'm using a svn version of numpy:

In [31]: numpy.__version__
Out[31]: '1.0.5.dev4767'

The problem is for an array larger than 256*256 the sum is going crazy.

In [45]: numpy.arange(256*256)
Out[45]: array([    0,     1,     2, ..., 65533, 65534, 65535])

In [46]: numpy.arange(256*256).sum()
Out[46]: 2147450880

In [47]: numpy.arange(257*257)
Out[47]: array([    0,     1,     2, ..., 66046, 66047, 66048])

In [48]: numpy.arange(257*257).sum()
Out[48]: -2113765120

>>> import numpy
>>> numpy.arange(256*256).sum()
2147450880
>>> numpy.arange(257*257).sum()
-2113765120
>>> numpy.__version__
'1.0.3'


Sorry for this bad news.

N.


ps: my system is an ubuntu linux 32



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