Mercurial > hg > ltpda

comparison m-toolbox/classes/+utils/@math/pfallps.m @ 0:f0afece42f48

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Import.
author Daniele Nicolodi <nicolodi@science.unitn.it>
date Wed, 23 Nov 2011 19:22:13 +0100
parents
children
comparison
equal deleted inserted replaced
-1:000000000000 0:f0afece42f48
1 % PFALLPS all pass filtering in order to stabilize TF poles and zeros.
2 %
3 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
4 % DESCRIPTION:
5 %
6 % All pass filtering in order to stabilize transfer function poles and
7 % zeros. It inputs a partial fraction expanded discrete model and
8 % outputs a pole-zero minimum phase system
9 %
10 % CALL:
11 %
12 % [resp,np] = pfallps(ir,ip,id,mresp,f)
13 % [resp,np] = pfallps(ir,ip,id,mresp,f,minphase)
14 % [resp,np,nz] = pfallps(ir,ip,id,mresp,f,minphase)
15 %
16 % INPUTS:
17 %
18 % ir: are residues
19 % ip: are poles
20 % id: is direct term
21 % f: is the frequancies vector in (Hz)
22 % minphase: is a flag assuming true (output a minimum phase system) or
23 % false (output a stable non minimum phase system) values. Default,
24 % true
25 %
26 % OUTPUTS:
27 %
28 % resp: is the minimum phase frequency response
29 % np: are new stable poles
30 % nz: are new stable zeros, this will be set only if minphase is set to
31 % false
32 %
33 % NOTE:
34 %
35 % This function make use of signal analysis toolbox functions
36 %
37 %
38 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
39 % VERSION: $Id: pfallps.m,v 1.7 2008/12/22 18:44:42 luigi Exp $
40 %
41 % HISTORY: 12-09-2008 L Ferraioli
42 % Creation
43 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
44 function varargout = pfallps(ir,ip,id,mresp,f,varargin)
45
46 % Reshaping
47 [a,b] = size(ir);
48 if a<b
49 ir = ir.'; % reshape as a column vector
50 end
51
52 [a,b] = size(ip);
53 if a<b
54 ip = ip.'; % reshape as a column vector
55 end
56
57 [a,b] = size(f);
58 if a<b
59 f = f.'; % reshape as a column vector
60 end
61
62 [a,b] = size(id);
63 if a > b
64 id = id.'; % reshape as a row
65 id = id(1,:); % taking the first row (the function can handle only simple constant direct terms)
66 end
67
68 if nargin == 6
69 minphase = varargin{1};
70 else
71 minphase = false;
72 end
73
74 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
75
76 % stabilizing poles
77 sp = p;
78 unst = real(sp) > 0;
79 sp(unst) = -1*conj(sp(unst));
80
81 [Na,Nb] = size(r);
82 for nn = 1:Nb
83
84 s = 1i.*2.*pi.*f;
85 pp = p(unst);
86 psp = sp(unst);
87 for ii = 1:length(s)
88 nterm = 1;
89 for jj = 1:length(sp(unst))
90 nterm = nterm.*(s(ii)-pp(jj))./(s(ii)-psp(jj));
91 end
92 phs(ii,1) = angle(nterm);
93 end
94
95 resp(:,nn) = mresp(:,nn).*(cos(phs)+1i.*sin(phs));
96
97 % output stable poles
98 np(:,nn) = sp;
99
100 if minphase
101 % finding zeros
102 [num,den] = residue(r,p,d);
103 zrs = roots(num);
104
105 % stabilizing zeros
106 szrs = zrs;
107 zunst = abs(zrs) > 1;
108 szrs(zunst) = 1./conj(zrs(zunst));
109
110 zzrs = zrs(zunst);
111 zszrs = szrs(zunst);
112 for ii = 1:length(s)
113 nterm = 1;
114 for jj = 1:length(szrs(zunst))
115 nterm = nterm.*(s(ii)-zszrs(jj))./(s(ii)-zzrs(jj));
116 end
117 zphs(ii,1) = angle(nterm);
118 end
119
120 resp(:,nn) = resp(:,nn).*(cos(zphs)+1i.*sin(zphs));
121
122 % output stable zeros
123 nz(:,nn) = szrs;
124 end
125 end
126 % output
127 if nargout == 1
128 varargout{1} = resp;
129 elseif nargout == 2
130 varargout{1} = resp;
131 varargout{2} = np;
132 elseif (nargout == 3) && minphase
133 varargout{1} = resp;
134 varargout{2} = np;
135 varargout{3} = nz;
136 else
137 error('Too many output arguments!')
138 end
139 end