[Scipy-tickets] [SciPy] #1343: divide warning for firwin with odd orders

SciPy Trac scipy-tickets@scipy....
Mon Dec 6 14:31:27 CST 2010


#1343: divide warning for firwin with odd orders
--------------------------+-------------------------------------------------
 Reporter:  mzim7372      |       Owner:  somebody
     Type:  defect        |      Status:  new     
 Priority:  high          |   Milestone:  0.9.0   
Component:  scipy.signal  |     Version:  0.8.0   
 Keywords:  firwin sinc   |  
--------------------------+-------------------------------------------------
 I receive the following warning:
 "Warning" invalid value encountered in divide" when calling firwin using
 an odd value for N. for example:

 {{{
 firwin(31, 0.25)
 }}}

 I've traced this to the line in the function with:

 {{{
 h = win*special.sinc(cutoff*m-alpha))
 }}}

 It seems to me that there is a problem with sinc(0). I believe that
 sinc(0) should equal 1. In scipy it does, but it throws a warning. I don't
 think it should.

-- 
Ticket URL: <http://projects.scipy.org/scipy/ticket/1343>
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