Hi,

I'm trying to create a digital filter using NeoDym, for some reason the filter doesn't seem to output any data, I am initializing it with this code:

double[] mathNetFiltercoefficients = MathNet.SignalProcessing.Filter.IIR.IirCoefficients.BandPass(samplingFrequency, (samplingFrequency / 4), 100);

//MathNet.SignalProcessing.Filter.OnlineFilter.CreateBandpass(MathNet.SignalProcessing.Filter.ImpulseResponse.Infinite, samplingFrequency, (samplingFrequency / 4) - 10, (samplingFrequency / 4) + 10);

//tried above way to initialize

 MathNetFilter1 = new MathNet.SignalProcessing.Filter.IIR.OnlineIirFilter(mathNetFiltercoefficients);

I have this line in a for loop to process the samples:

filteredSample = MathNetFilter1.ProcessSample(sampleToProcess);

I am not sure what I did wrong here, also is the Math.net numerics take over signal processing in the future?

cheers,

Jamie

Hi Jamie

Indeed, there seems to be an issue in the OnlineIirFilter class in the current master branch.

In a quick code scan, Line 81 of IirFilter.cs looks suspicious, but I'll need to check and verify the whole code base (and upgrade it to .Net 4 and VS2010 while we're at it).

Thanks,
Chris

Hi Chris,

Ok well I am using a lot of filters in a project I am working on so I can do some rigorous testing if you want let me know :D

cheers,

Jamie

Hi there,

I've got the same problem when I'm using OnlineIirFilter.

So, I decided to fix the problem, but I've got some questions about the code :

- The variable un is reinitialized in each loop. I don't understand why.

- What are leftcoefficients et rightcoefficients? (thanks to wikipedia, I think it's a and b coefficient, but I'm not sure)

Finaly, is there someone who already fix this problem?

Thanks!

Hi all,

Did anyone come up with a fix for this? As above, I've found the IirFilter to be broken.

Thanks.