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From Clemens Novak <>
Subject Re: [math] Convolution
Date Thu, 23 Aug 2012 12:31:47 GMT
On 2012-08-20 19:25, Luc Maisonobe wrote:
> Le 20/08/2012 17:00, Clemens Novak a écrit :
>> Dear all,
> Hi Clemens,
>> I would like to work on some signal processing functions (as 
>> indicated
>> on the wiki WishList) and started with the convolution of 2 
>> sequences
>> (represented as RealVector). I have completed a first working 
>> version
>> (some error checking code, formatting, unit tests etc are missing); 
>> I am
>> unsure of how to continue: Is the next step to create a new Jira 
>> ticket
>> and upload my final code there (for further discussion/review/...)?
> Yes, you can do that.
>> Thanks for your help & kind regards - Clemens
> Thanks for your interest and contribution.
> Luc
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Dear all,

besides the ongoing discussions in MATH-851, I would like to discuss 
some extensions of this library in the area of discrete-time signal 

(1) convolution of 1D and 2D sequences based on (i) straightforward 
calculation of the convolution sum and (ii) using the FFT.

(2) filter functions for 1D sequences, i.e. y[n] = \sum_{l=0}^{L-1} b_l 
x[n-l] - \sum_{m=1}^{M-1} a_m y[n-m]

(3) window functions (such as raised cosine, blackmann...) used in 
conjunction with FFTs

(4) possibly some basic filter design (such as window method, 
Parks-McClellan algorithm...)

However, first I want to ensure that you think these topics belong in 
Commons math - I have been reading the intro (... is a library of 
lightweight, self-contained mathematics and statistics components 
addressing the most common problems...) and I am not perfectly sure 
whether these topics really fit here?

In MATH-851 we shortly touched whether using RealVector or a simple 
double array is better. What's your opinion here? The double array might 
be better in terms of performance; when based on RealVector, however, 
more basic functionality would be provided out of the box. Has anyone 
made a performance comparison between arrays and RealVector in order to 
have some guidelines here?

Kind regards - Clemens

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