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cz2iir

PURPOSE ^

Return a,b IIR filter coefficients for a complex zero

SYNOPSIS ^

function [a,b] = cz2iir(z, fs)

DESCRIPTION ^

 Return a,b IIR filter coefficients for a complex zero
 designed using the bilinear transform.
 
 usage: [a,b] = cz2iir(z, fs)
 
  z  - zero object
  fs - the sample rate for the filter
 
  M Hewitson 03-04-07
 
 $Id: cz2iir.html,v 1.1 2007/06/08 14:15:09 hewitson Exp $

CROSS-REFERENCE INFORMATION ^

This function calls: This function is called by:

SOURCE CODE ^

0001 function [a,b] = cz2iir(z, fs)
0002 
0003 % Return a,b IIR filter coefficients for a complex zero
0004 % designed using the bilinear transform.
0005 %
0006 % usage: [a,b] = cz2iir(z, fs)
0007 %
0008 %  z  - zero object
0009 %  fs - the sample rate for the filter
0010 %
0011 %  M Hewitson 03-04-07
0012 %
0013 % $Id: cz2iir.html,v 1.1 2007/06/08 14:15:09 hewitson Exp $
0014 %
0015 
0016 f0 = get(z, 'f');
0017 q  = get(z, 'q');
0018 
0019 w0 = f0*2*pi;
0020 w02 = w0^2;
0021 
0022 a(1) = (-q*w02/2 - 2*q*fs*fs - w0*fs) / (q*w02);
0023 a(2) = (-w02+4*fs*fs) / w02;
0024 a(3) = (-q*w02/2 - 2*q*fs*fs + w0*fs) / (q*w02);
0025 
0026 b(1) = 1;
0027 b(2) = -2;
0028 b(3) = -1;
0029 
0030 % END

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