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[project @ 2004-02-17 02:34:33 by jwe]
author jwe
date Tue, 17 Feb 2004 02:34:33 +0000
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1 ## Copyright (C) 1996, 1998 Auburn University. All rights reserved.
2 ##
3 ## This file is part of Octave.
4 ##
5 ## Octave is free software; you can redistribute it and/or modify it
6 ## under the terms of the GNU General Public License as published by the
7 ## Free Software Foundation; either version 2, or (at your option) any
8 ## later version.
9 ##
10 ## Octave is distributed in the hope that it will be useful, but WITHOUT
11 ## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 ## FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 ## for more details.
14 ##
15 ## You should have received a copy of the GNU General Public License
16 ## along with Octave; see the file COPYING. If not, write to the Free
17 ## Software Foundation, 59 Temple Place, Suite 330, Boston, MA 02111 USA.
18
19 ## -*- texinfo -*-
20 ## @deftypefn {Function File} {} zp (@var{zer}, @var{pol}, @var{k}, @var{tsam}, @var{inname}, @var{outname})
21 ## Create system data structure from zero-pole data.
22 ##
23 ## @strong{Inputs}
24 ## @table @var
25 ## @item zer
26 ## vector of system zeros
27 ## @item pol
28 ## vector of system poles
29 ## @item k
30 ## scalar leading coefficient
31 ## @item tsam
32 ## sampling period. default: 0 (continuous system)
33 ## @item inname
34 ## @itemx outname
35 ## input/output signal names (lists of strings)
36 ## @end table
37 ##
38 ## @strong{Outputs}
39 ## sys: system data structure
40 ##
41 ## @strong{Example}
42 ## @example
43 ## octave:1> sys=zp([1 -1],[-2 -2 0],1);
44 ## octave:2> sysout(sys)
45 ## Input(s)
46 ## 1: u_1
47 ## Output(s):
48 ## 1: y_1
49 ## zero-pole form:
50 ## 1 (s - 1) (s + 1)
51 ## -----------------
52 ## s (s + 2) (s + 2)
53 ## @end example
54 ## @end deftypefn
55
56 ## Modified by John Ingram July 20, 1996
57
58 function outsys = zp (zer, pol, k, tsam, inname, outname)
59
60 ## Test for the correct number of input arguments
61 if ((nargin < 3) || (nargin > 6))
62 usage("outsys = zp(zer,pol,k[,tsam,inname,outname])");
63 endif
64
65 ## check input format
66 if( ! (isvector(zer) | isempty(zer) ) )
67 error("zer must be a vector or empty");
68 endif
69 if(!isempty(zer))
70 zer = reshape(zer,1,length(zer)); # make it a row vector
71 endif
72
73 if( ! (isvector(pol) | isempty(pol)))
74 error("pol must be a vector");
75 endif
76 if(!isempty(pol))
77 pol = reshape(pol,1,length(pol));
78 endif
79
80 if (! isscalar(k))
81 error("k must be a scalar");
82 endif
83
84 ## Test proper numbers of poles and zeros. The number of poles must be
85 ## greater than or equal to the number of zeros.
86 if (length(zer) > length(pol))
87 error(["number of poles (", num2str(length(pol)), ...
88 ") < number of zeros (", num2str(length(zer)),")"]);
89 endif
90
91 ## Set the system transfer function
92 outsys.zer = zer;
93 outsys.pol = pol;
94 outsys.k = k;
95
96 ## Set the system vector: active = 1, updated = [0 1 0];
97 outsys.sys = [1, 0, 1, 0];
98
99 ## Set defaults
100 outsys.tsam = 0;
101 outsys.n = length(pol);
102 outsys.nz = 0;
103 outsys.yd = 0; # assume (for now) continuous time outputs
104
105 ## Set the type of system
106 if (nargin > 3)
107 if( !isscalar(tsam) )
108 error("tsam must be a nonnegative scalar");
109 endif
110 if (tsam < 0)
111 error("sampling time must be positve")
112 elseif (tsam > 0)
113 [outsys.n,outsys.nz] = swap(outsys.n, outsys.nz);
114 outsys.yd = 1; # discrete-time output
115 endif
116
117 outsys.tsam = tsam;
118 endif
119
120 outsys.inname = __sysdefioname__ (1, "u");
121 outsys.outname = __sysdefioname__ (1, "y");
122 outsys.stname = __sysdefstname__ (outsys.n, outsys.nz);
123
124 ## Set name of input
125 if (nargin > 4)
126 ## make sure its a string
127 if(!isempty(inname))
128 if(!iscell(inname))
129 inname = {inname};
130 endif
131 if(!is_signal_list(inname))
132 error("inname must be a single signal name");
133 endif
134 outsys.inname = inname(1);
135 endif
136 endif
137
138 ## Set name of output
139 if (nargin > 5)
140 if(!isempty(outname))
141 if(!iscell(outname))
142 outname = {outname};
143 endif
144 if(!is_signal_list(outname))
145 error("outname must be a single signal name");
146 endif
147 outsys.outname = outname(1);
148 endif
149 endif
150
151 endfunction