[Scipy-tickets] [SciPy] #396: Small bug in documentation signal.lfilter

SciPy scipy-tickets@scipy....
Fri Apr 13 17:03:06 CDT 2007


#396: Small bug in documentation   signal.lfilter
--------------------------+-------------------------------------------------
 Reporter:  stef          |       Owner:  somebody
     Type:  defect        |      Status:  new     
 Priority:  normal        |   Milestone:          
Component:  scipy.signal  |     Version:          
 Severity:  trivial       |    Keywords:          
--------------------------+-------------------------------------------------
 Small bug in documentation   signal.lfilter


 {{{
 lfilter(b, a, x, axis=-1, zi=None)
 <snip>
     Algorithm:
       The filter function is implemented as a direct II transposed
 structure.
       This means that the filter implements
       y[n] = b[0]*x[n] + b[1]*x[n-1] + ... + b[nb]*x[n-nb]
                        - a[1]*y[n-1] + ... + a[na]*y[n-na]

 should be
       y[n] = b[0]*x[n] + b[1]*x[n-1] + ... + b[nb]*x[n-nb]
                        - a[1]*y[n-1] - ... - a[na]*y[n-na]

 or this might even be better
       a[0]*y[n] = b[0]*x[n] + b[1]*x[n-1] + ... + b[nb]*x[n-nb]
                             - a[1]*y[n-1] - ... - a[na]*y[n-na]

 }}}

-- 
Ticket URL: <http://projects.scipy.org/scipy/scipy/ticket/396>
SciPy <http://www.scipy.org/>
SciPy is open-source software for mathematics, science, and engineering.


More information about the Scipy-tickets mailing list