[Scipy-tickets] [SciPy] #1665: Are odd-length window functions supposed to be always symmetrical?

SciPy Trac scipy-tickets@scipy....
Wed May 30 14:51:23 CDT 2012

```#1665: Are odd-length window functions supposed to be always symmetrical?
--------------------------+-------------------------------------------------
Reporter:  endolith      |       Owner:  cdavid
Type:  defect        |      Status:  new
Priority:  normal        |   Milestone:  Unscheduled
Component:  scipy.signal  |     Version:  0.10.0
Keywords:                |
--------------------------+-------------------------------------------------
The window functions in scipy.signal have a `sym` option for producing
symmetric windows or periodic windows, but if you create a periodic window
of an odd size, it gives identical output to a symmetric window.  This is
in the code, but is it right?  It doesn't match Matlab's behavior, as
described [https://ccrma.stanford.edu/~jos/sasp/Matlab_Hamming_Window.html
here].

If it's right, it should be documented why it works this way

{{{
>> hamming(3) % same in Matlab and Octave
ans =
0.0800
1.0000
0.0800
>> hamming(3,'symmetric') % Matlab only
ans =
0.0800
1.0000
0.0800
>> hamming(3,'periodic') % Matlab only
ans =
0.0800
0.7700
0.7700
>> hamming(4) % same in Matlab and Octave
ans =
0.0800
0.7700
0.7700
0.0800
}}}

SciPy:

{{{

In [2]: hamming(3)
Out[2]: array([ 0.08,  1.  ,  0.08])

In [3]: hamming(3,sym=True)
Out[3]: array([ 0.08,  1.  ,  0.08])

In [4]: hamming(3,sym=False)
Out[4]: array([ 0.08,  1.  ,  0.08])

In [5]: hamming(4)
Out[5]: array([ 0.08,  0.77,  0.77,  0.08])

In [6]: hamming(4, sym=True)
Out[6]: array([ 0.08,  0.77,  0.77,  0.08])

In [7]: hamming(4, sym=False)
Out[7]: array([ 0.08,  0.54,  1.  ,  0.54])
}}}

--
Ticket URL: <http://projects.scipy.org/scipy/ticket/1665>
SciPy <http://www.scipy.org>
SciPy is open-source software for mathematics, science, and engineering.
```

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