view m-toolbox/classes/+utils/@math/pfallps.m @ 24:056f8e1e995e
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Properly record history in fromRepository constructors
author
Daniele Nicolodi <nicolodi@science.unitn.it>
date
Mon, 05 Dec 2011 16:20:06 +0100 (2011-12-05)
parents
f0afece42f48
children
line source
+ − % PFALLPS all pass filtering in order to stabilize TF poles and zeros.
+ − %
+ − %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+ − % DESCRIPTION:
+ − %
+ − % All pass filtering in order to stabilize transfer function poles and
+ − % zeros. It inputs a partial fraction expanded discrete model and
+ − % outputs a pole-zero minimum phase system
+ − %
+ − % CALL:
+ − %
+ − % [resp,np] = pfallps(ir,ip,id,mresp,f)
+ − % [resp,np] = pfallps(ir,ip,id,mresp,f,minphase)
+ − % [resp,np,nz] = pfallps(ir,ip,id,mresp,f,minphase)
+ − %
+ − % INPUTS:
+ − %
+ − % ir: are residues
+ − % ip: are poles
+ − % id: is direct term
+ − % f: is the frequancies vector in (Hz)
+ − % minphase: is a flag assuming true (output a minimum phase system) or
+ − % false (output a stable non minimum phase system) values. Default,
+ − % true
+ − %
+ − % OUTPUTS:
+ − %
+ − % resp: is the minimum phase frequency response
+ − % np: are new stable poles
+ − % nz: are new stable zeros, this will be set only if minphase is set to
+ − % false
+ − %
+ − % NOTE:
+ − %
+ − % This function make use of signal analysis toolbox functions
+ − %
+ − %
+ − %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+ − % VERSION: $Id: pfallps.m,v 1.7 2008/12/22 18:44:42 luigi Exp $
+ − %
+ − % HISTORY: 12-09-2008 L Ferraioli
+ − % Creation
+ − %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+ − function varargout = pfallps(ir,ip,id,mresp,f,varargin)
+ −
+ − % Reshaping
+ − [a,b] = size(ir);
+ − if a<b
+ − ir = ir.'; % reshape as a column vector
+ − end
+ −
+ − [a,b] = size(ip);
+ − if a<b
+ − ip = ip.'; % reshape as a column vector
+ − end
+ −
+ − [a,b] = size(f);
+ − if a<b
+ − f = f.'; % reshape as a column vector
+ − end
+ −
+ − [a,b] = size(id);
+ − if a > b
+ − id = id.'; % reshape as a row
+ − id = id(1,:); % taking the first row (the function can handle only simple constant direct terms)
+ − end
+ −
+ − if nargin == 6
+ − minphase = varargin{1};
+ − else
+ − minphase = false;
+ − end
+ −
+ − %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+ −
+ − % stabilizing poles
+ − sp = p;
+ − unst = real(sp) > 0;
+ − sp(unst) = -1*conj(sp(unst));
+ −
+ − [Na,Nb] = size(r);
+ − for nn = 1:Nb
+ −
+ − s = 1i.*2.*pi.*f;
+ − pp = p(unst);
+ − psp = sp(unst);
+ − for ii = 1:length(s)
+ − nterm = 1;
+ − for jj = 1:length(sp(unst))
+ − nterm = nterm.*(s(ii)-pp(jj))./(s(ii)-psp(jj));
+ − end
+ − phs(ii,1) = angle(nterm);
+ − end
+ −
+ − resp(:,nn) = mresp(:,nn).*(cos(phs)+1i.*sin(phs));
+ −
+ − % output stable poles
+ − np(:,nn) = sp;
+ −
+ − if minphase
+ − % finding zeros
+ − [num,den] = residue(r,p,d);
+ − zrs = roots(num);
+ −
+ − % stabilizing zeros
+ − szrs = zrs;
+ − zunst = abs(zrs) > 1;
+ − szrs(zunst) = 1./conj(zrs(zunst));
+ −
+ − zzrs = zrs(zunst);
+ − zszrs = szrs(zunst);
+ − for ii = 1:length(s)
+ − nterm = 1;
+ − for jj = 1:length(szrs(zunst))
+ − nterm = nterm.*(s(ii)-zszrs(jj))./(s(ii)-zzrs(jj));
+ − end
+ − zphs(ii,1) = angle(nterm);
+ − end
+ −
+ − resp(:,nn) = resp(:,nn).*(cos(zphs)+1i.*sin(zphs));
+ −
+ − % output stable zeros
+ − nz(:,nn) = szrs;
+ − end
+ − end
+ − % output
+ − if nargout == 1
+ − varargout{1} = resp;
+ − elseif nargout == 2
+ − varargout{1} = resp;
+ − varargout{2} = np;
+ − elseif (nargout == 3) && minphase
+ − varargout{1} = resp;
+ − varargout{2} = np;
+ − varargout{3} = nz;
+ − else
+ − error('Too many output arguments!')
+ − end
+ − end