Simple Implementation of MATHNET Filtering Lowpass filter

Question

I have created the following code:

Double[] ArrayOfData = new Double[Size] { 0.5, 1.5, ... , 1.0 };
var lowPass = MathNet.Filtering.IIR.IirCoefficients.LowPass(0, 0, 0);

MathNet.Filtering.IIR.OnlineIirFilter filter = new MathNet.Filtering.IIR.OnlineIirFilter(lowPass);

filter.ProcessSamples(ArrayOfData);

The problem that I am running into is that the low pass filter does not seem to do anything. I have tried different values than 0,0,0 for the lowpass but it doesn't seem to have any effect.

If anyone has some knowledge on the MathNet Filtering api, could you show a simple example or explain what I am doing incorrectly?

The nuget info can be found: http://filtering.mathdotnet.com/

It is the MathNet.Filtering - core package link that I am using.

score 4 · Accepted Answer · answered Jun 29 '16 at 09:36

First of all, please note that the ProcessSamples method returns the filtered data; ArrayOfData is left unmodified. You thus need to obtain the method output to be able to look at the results:

var processed = filter.ProcessSamples(ArrayOfData);

Second, the parameter combination (0, 0, 0) is invalid. Arguments are samplingRate (samples per unit), cutoff (cutoff frequency in samples per unit), and width (bandwidth in samples per unit), and as far as I know these arguments all need to be larger than zero.

It may be late but here is your check mark! Thank you. – Maderas Sep 26 '17 at 13:04 — Maderas, Sep 26 '17 at 13:04

Simple Implementation of MATHNET Filtering Lowpass filter

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