[Numpy-discussion] problem w 32bit binomial?
David Warde-Farley
dwf@cs.toronto....
Thu Feb 25 18:32:54 CST 2010
Hey James,
On 25-Feb-10, at 5:59 PM, James Bergstra wrote:
> In case this hasn't been solved in more recent numpy...
>
> I've tried the following lines on two installations of numpy 1.3
> with python 2.6
>
> numpy.random.binomial(n=numpy.asarray([2,3,4], dtype='int64'),
> p=numpy.asarray([.1, .2, .3], dtype='float64'))
>
> A 64bit computer gives an output of array length 3.
> A 32bit computer gives an error:
>
> TypeError: array cannot be safely cast to required type
It seems to be not only 32-bit specific but x86-specific. On a ppc
machine, 32-bit mode:
dwf@morrislab:~$ python-32
Python 2.6.4 (r264:75706, Feb 16 2010, 21:03:46)
[GCC 4.0.1 (Apple Inc. build 5493)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import numpy
>>> numpy.__version__
'1.3.0'
>>> numpy.random.binomial(n=numpy.asarray([2,3,4], dtype='int64'),
p=numpy.asarray([.1,.2,.3], dtype='float64'))
array([1, 1, 2])
But I can confirm the bug on OS X/Intel 32-bit, and Linux x86-32 (both
1.3.0 and most recent svn trunk), as well as its absence on Linux
x86-64. The problem seems to be with this line in mtrand.pyx, line
3306 in the trunk:
on = <ndarray>PyArray_FROM_OTF(n, NPY_LONG, NPY_ALIGNED)
I recall there being some consistency problems with NPY_LONG across
architectures. I thought it was only an issue for Python 2.4,
though... Perhaps Chuck or David C. know what's going on.
David
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