Mercurial > hg > ltpda
comparison m-toolbox/classes/@pz/fq2ri.m @ 0:f0afece42f48
Import.
| author | Daniele Nicolodi <nicolodi@science.unitn.it> |
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| date | Wed, 23 Nov 2011 19:22:13 +0100 |
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| -1:000000000000 | 0:f0afece42f48 |
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| 1 % FQ2RI Convert frequency/Q pole/zero representation | |
| 2 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% | |
| 3 % | |
| 4 % DESCRIPTION: FQ2RI Convert frequency/Q pole/zero representation into: | |
| 5 % -Q=Nan: real pole/zero [output: ri] | |
| 6 % -Q>0.5 real and imaginary conjugate pairs [ri conj(ri)] | |
| 7 % -Q=0.5 two equal real poles [ri ri] | |
| 8 % -Q<0.5 two real poles [ri ri] | |
| 9 % | |
| 10 % CALL: ri= fq2ri(f0, Q) | |
| 11 % | |
| 12 % VERSION: $Id: fq2ri.m,v 1.10 2011/02/18 16:48:54 ingo Exp $ | |
| 13 % | |
| 14 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% | |
| 15 | |
| 16 function ri= fq2ri(f0, Q) | |
| 17 | |
| 18 if(nargin==0) | |
| 19 disp('usage: ri = fq2ri2(f0, Q)') | |
| 20 return | |
| 21 elseif(nargin==1 || nargin==2 && isnan(Q)) | |
| 22 ri = -((2*pi*f0)); | |
| 23 elseif(nargin==2 && Q>=0) | |
| 24 if Q < 0.5 | |
| 25 disp('!!! Q < 0.5! Splitting to two real poles/zeros;') | |
| 26 a = 2*pi*f0/(2*Q)*(1+sqrt(1-4*Q^2)); | |
| 27 b = 2*pi*f0/(2*Q)*(1-sqrt(1-4*Q^2)); | |
| 28 ri = [a b]; | |
| 29 elseif Q == 0.5 | |
| 30 disp('!!! Q = 0.5! Returning two equal real poles/zeros;') | |
| 31 w0 = 2*pi*f0; | |
| 32 re = w0/(2*Q); | |
| 33 ri = [re re]; | |
| 34 else | |
| 35 w0 = 2*pi*f0; | |
| 36 re = -w0/(2*Q); | |
| 37 im = w0*sqrt(1-1/(4*Q^2)); | |
| 38 tri = complex(re,im); | |
| 39 ri = [tri; conj(tri)]; | |
| 40 end | |
| 41 | |
| 42 end | |
| 43 |