Mercurial > hg > ltpda

comparison m-toolbox/classes/@pz/resp.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 % RESP returns the complex response of the pz object.
2 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
3 %
4 % DESCRIPTION: RESP returns the complex response of the pz object. The
5 % response is computed assuming that object represents a pole.
6 % If the object represents a zero, just take the inverse of
7 % the returned response: 1./r.
8 %
9 % CALL: [f,r] = resp(p, f); % compute response for vector f
10 % [f,r] = resp(p, f1, f2, nf); % compute response from f1 to f2
11 % % in nf steps.
12 % [f,r] = resp(p, f1, f2, nf, scale); % compute response from f1 to f2
13 % % in nf steps using scale ['lin' or 'log'].
14 % [f,r] = resp(p); % compute response
15 %
16 % REMARK: This is just a helper function. This function should only be
17 % called from class functions.
18 %
19 % VERSION: $Id: resp.m,v 1.9 2011/02/18 16:48:54 ingo Exp $
20 %
21 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
22
23 function [f,r] = resp(varargin)
24
25 %%% Input objects checks
26 if nargin < 1
27 error('### incorrect number of inputs.')
28 end
29
30 %%% look at inputs
31 p = varargin{1};
32 if ~isa(p, 'pz')
33 error('### first argument should be a pz object.');
34 end
35
36 %%% decide whether we modify the pz-object, or create a new one.
37 p = copy(p, nargout);
38
39 %%% Now look at the pole
40 f0 = p.f;
41 Q = p.q;
42
43 %%% Define frequency vector
44 f = [];
45
46 if nargin == 1
47 f1 = f0/10;
48 f2 = f0*10;
49 nf = 1000;
50 scale = 'lin';
51 elseif nargin == 2
52 f = varargin{2};
53 elseif nargin == 4
54 f1 = varargin{2};
55 f2 = varargin{3};
56 nf = varargin{4};
57 scale = 'lin';
58 elseif nargin == 5
59 f1 = varargin{2};
60 f2 = varargin{3};
61 nf = varargin{4};
62 scale = varargin{5};
63 else
64 error('### incorrect number of inputs.');
65 end
66
67 %%% Build f if we need it
68 if isempty(f)
69 switch lower(scale)
70 case 'lin'
71 f = linspace(f1, f2, nf);
72 case 'log'
73 f = logspace(log10(f1), log10(f2), nf);
74 end
75 end
76
77
78 %%% Now compute the response
79 if Q>=0.5
80 re = 1 - (f.^2./f0^2);
81 im = f ./ (f0*Q);
82 r = 1./complex(re, im);
83 else
84 re = 1;
85 im = f./f0;
86 r = 1./complex(re, im);
87 end
88 end
89