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comparison m-toolbox/classes/+utils/@math/pfallpz2.m @ 0:f0afece42f48

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author Daniele Nicolodi <nicolodi@science.unitn.it>
date Wed, 23 Nov 2011 19:22:13 +0100
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1 % PFALLPZ2 all pass filtering 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] = pfallpz2(ip,mresp,f,fs)
13 %
14 % INPUTS:
15 %
16 % ip: are poles
17 % f: is the frequancies vector in (Hz)
18 % fs: is the sampling frequency in (Hz)
19 %
20 % OUTPUTS:
21 %
22 % resp: is the functions phase frequency response
23 % np: are the new stable poles
24 %
25 % NOTE:
26 %
27 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
28 % VERSION: $Id: pfallpz.m,v 1.6 2009/06/10 15:47:00 luigi Exp $
29 %
30 % HISTORY: 12-09-2008 L Ferraioli
31 % Creation
32 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
33 function varargout = pfallpz2(ip,mresp,f,fs)
34
35 [a,b] = size(ip);
36 if a<b
37 ip = ip.'; % reshape as a column vector
38 end
39
40 [a,b] = size(f);
41 if a<b
42 f = f.'; % reshape as a column vector
43 end
44
45 if isempty(fs)
46 fs = 1;
47 end
48 [a,b] = size(fs);
49 if a ~= b
50 disp(' Fs has to be a number. Only first term will be considered! ')
51 fs = fs(1);
52 end
53
54
55 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
56
57 Nb = numel(ip);
58 for nn = 1:Nb
59
60 p = ip(nn).poles;
61
62 % stabilizing poles
63 sp = p;
64 unst = abs(p) > 1;
65 sp(unst) = conj(sp(unst));
66
67 pp = p(unst);
68 psp = sp(unst);
69 allpstr = '(1';
70 for jj = 1:numel(sp(unst))
71 allpstr = [allpstr sprintf('.*((z-%0.20d)./(z*%0.20d-1))',pp(jj),psp(jj))];
72 end
73 allpstr = [allpstr ')'];
74
75 funcell{nn} = allpstr;
76
77 end
78
79 z = cos((2*pi/fs).*f) + 1i.*sin((2*pi/fs).*f);
80 fullallprsp = 1;
81
82 for nn = 1:Nb
83
84 nterm = eval(funcell{nn});
85 % willing to work with columns
86 if size(nterm,2)>1
87 nterm = nterm.';
88 end
89
90 allprsp(:,nn) = nterm;
91
92 fullallprsp = fullallprsp.*nterm;
93
94 end
95
96 phs = angle(fullallprsp);
97
98 for kk=1:Nb
99 resp(:,kk) = mresp(:,kk).*(cos(phs)+1i.*sin(phs));
100 end
101
102
103 % output
104 if nargout == 1
105 varargout{1} = resp;
106 else
107 error('Too many output arguments!')
108 end
109 end
110
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