[Numpy-discussion] New functions.

Bruce Southey bsouthey@gmail....
Wed Jun 1 11:11:06 CDT 2011


On 06/01/2011 11:01 AM, Robert Kern wrote:
> On Wed, Jun 1, 2011 at 10:44, Craig Yoshioka<craigyk@me.com>  wrote:
>> would anyone object to fixing the numpy mean and stdv functions, so that they always used a 64-bit value to track sums, or so that they used a running calculation.  That way
>>
>> np.mean(np.zeros([4000,4000],'f4')+500)
>>
>> would not equal 511.493408?
> Yes, I object. You can set the accumulator dtype explicitly if you
> need it: np.mean(arr, dtype=np.float64)
>
Sure but fails to address that the output dtype of mean in this case is 
np.float64 which one would naively assume is also np.float64:
 >>> np.mean(np.zeros([4000,4000],'f4')+500).dtype
dtype('float64')

Thus, we have:
Tickets 465 and 518
http://projects.scipy.org/numpy/ticket/465
http://projects.scipy.org/numpy/ticket/518

Various threads as well such as:
http://mail.scipy.org/pipermail/numpy-discussion/2010-December/054253.html

Bruce


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