[Numpy-tickets] [NumPy] #388: Doc error for std in http://scipy.org/Numpy_Example_List#std
NumPy
numpy-tickets at scipy.net
Wed Nov 22 09:29:01 CST 2006
#388: Doc error for std in http://scipy.org/Numpy_Example_List#std
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Reporter: g2boojum | Owner: somebody
Type: defect | Status: new
Priority: normal | Milestone:
Component: Other | Version:
Severity: normal | Keywords:
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According to the example in http://scipy.org/Numpy_Example_List#std,
array.std() uses an N-1 normalization
(and that's what the example shows). With numpy-1.0 on my machine:
In [22]: a = array([1., 2., 7.])
In [23]: a.std()
Out[23]: 2.62466929134
In [24]: sqrt(((1.-a.mean())**2 + (2.-a.mean())**2 + (7.-a.mean())**2)/3)
Out[24]: 2.6246692913372702
In [25]: sqrt(((1.-a.mean())**2 + (2.-a.mean())**2 + (7.-a.mean())**2)/2)
Out[25]: 3.214550253664318 <-- That's the result in the example
Please fix the docs.
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Ticket URL: <http://projects.scipy.org/scipy/numpy/ticket/388>
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