Difference between revisions of "Contributions:IIRFilter ML"
(Created page with "==Synopsis== A finite impulse response (IIR) filter for temporal filtering that behaves like Matlab's <tt>filter()</tt> function. ==Location== http://{{SERVERNAME}}/svn/trunk...") 
(No difference)

Latest revision as of 15:15, 19 August 2019
Contents
Synopsis
A finite impulse response (IIR) filter for temporal filtering that behaves like Matlab's filter() function.
Location
http://www.bci2000.org/svn/trunk/src/contrib/SignalProcessing/IIRFilter_ML
Versioning
Authors
Juergen Mellinger
Source Code Revisions
 Initial development: 6005
 Tested under: 6008
 Known to compile under: 6008
 Broken since: 
Matlab filter() Function
The Matlab filter() function is a direct form II transposed implementation of the IIR difference equation. If are the denominator coefficients of the filter polynomial, and are the numerator coefficients of the filter polynomial, and the shorter of the two is padded with zeros, then the direct form II implementation computes the filter's output at sample as
where is the input, is the output, and are the filter delays.
Parameters
NumeratorB
List of numerator coefficients for the filter polynomial. Corresponds to the b parameter of the Matlab filter() function.
DenominatorA
List of denominator coefficients for the filter polynomial. Corresponds to the a parameter of the Matlab filter() function. The list must contain at least one value, and that value must be nonzero. All coefficients of the filter polynomial will be normalized dividing by the first entry of DenominatorA.
NumeratorB and DenominatorA coefficients will be applied to all channels; it is not possible to specify indiviual coefficients for channels.
DelaysZi
Matrix of individual initial values of the filter delays. Corresponds to the zi parameter of the Matlab filter() function. Columns correspond to channels, rows correspond to delays.
If empty, filter delays are filled with zeros. At the end of each run, the DelaysZi parameter is updated with the current values of the delays, i.e. the value of the zf parameter in Matlab.
States
None.