[SciPy-user] Re: data smoothing: interpolate.splrep ignores s parameter

Travis E. Oliphant oliphant at ee.byu.edu
Wed Feb 25 16:43:30 CST 2004


Pearu Peterson wrote:
> 
> On Wed, 25 Feb 2004, george young wrote:
> 
> FFT is not suitable here as your data is not periodic. But if you need 
> only derivatives, then use

This is not necessarily true.  The FFT can be used for non-periodic data 
  -- and is in fact used quite often for such cases as long as you are 
careful.  You just have to realize that the FFT is assuming your data is 
periodic and so any filtering (i.e. smoothing) will be using wrap-around 
boundary conditions.

You can window your data, zero-pad, mirror it on the boundaries and many 
other things in order to get rid of artifacts that result from the 
periodic assumption of the FFT.


-Travis O.



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