[Scipy-tickets] [SciPy] #1410: Incorrect calculation of extended signal in signal.filtfilt

SciPy Trac scipy-tickets@scipy....
Mon Mar 14 21:11:02 CDT 2011


#1410: Incorrect calculation of extended signal in signal.filtfilt
------------------------------+---------------------------------------------
 Reporter:  warren.weckesser  |       Owner:  somebody
     Type:  defect            |      Status:  new     
 Priority:  normal            |   Milestone:  0.10.0  
Component:  scipy.signal      |     Version:  0.9.0   
 Keywords:                    |  
------------------------------+---------------------------------------------

Old description:

> The function signal.filtfilt extends the input signal x on both ends with
> this code:
> {{{
>     s=r_[2*x[0]-x[edge:1:-1],x,2*x[-1]-x[-1:-edge:-1]]
> }}}
> where edge is an integer that is three times the filter length.  The
> attached plot shows the values when edge = 11 and the x = np.linspace(0,
> 10, 11).  Presumably the data should be a straight line.

New description:

 The function signal.filtfilt extends the input signal x on both ends with
 this code:
 {{{
     s=r_[2*x[0]-x[edge:1:-1],x,2*x[-1]-x[-1:-edge:-1]]
 }}}
 where edge is an integer that is three times the filter length.  The
 attached plot shows the values when edge = 10 and the x = np.linspace(0,
 10, 11).  Presumably the data should be a straight line.

--

Comment(by warren.weckesser):

 Fixed value of edge mentioned in the description.

-- 
Ticket URL: <http://projects.scipy.org/scipy/ticket/1410#comment:2>
SciPy <http://www.scipy.org>
SciPy is open-source software for mathematics, science, and engineering.


More information about the Scipy-tickets mailing list