/usr/share/octave/packages/control-3.0.0/zpk.m is in octave-control 3.0.0-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 | ## Copyright (C) 2009-2015 Lukas F. Reichlin
##
## This file is part of LTI Syncope.
##
## LTI Syncope is free software: you can redistribute it and/or modify
## it under the terms of the GNU General Public License as published by
## the Free Software Foundation, either version 3 of the License, or
## (at your option) any later version.
##
## LTI Syncope is distributed in the hope that it will be useful,
## but WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
## GNU General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with LTI Syncope. If not, see <http://www.gnu.org/licenses/>.
## -*- texinfo -*-
## @deftypefn {Function File} {@var{s} =} zpk (@var{'s'})
## @deftypefnx {Function File} {@var{z} =} zpk (@var{'z'}, @var{tsam})
## @deftypefnx {Function File} {@var{sys} =} zpk (@var{sys})
## @deftypefnx {Function File} {@var{sys} =} zpk (@var{k}, @dots{})
## @deftypefnx {Function File} {@var{sys} =} zpk (@var{z}, @var{p}, @var{k}, @dots{})
## @deftypefnx {Function File} {@var{sys} =} zpk (@var{z}, @var{p}, @var{k}, @var{tsam}, @dots{})
## @deftypefnx {Function File} {@var{sys} =} zpk (@var{z}, @var{p}, @var{k}, @var{tsam}, @dots{})
## Create transfer function model from zero-pole-gain data.
## This is just a stop-gap compatibility wrapper since zpk
## models are not yet implemented.
##
## @strong{Inputs}
## @table @var
## @item sys
## @acronym{LTI} model to be converted to transfer function.
## @item z
## Cell of vectors containing the zeros for each channel.
## z@{i,j@} contains the zeros from input j to output i.
## In the SISO case, a single vector is accepted as well.
## @item p
## Cell of vectors containing the poles for each channel.
## p@{i,j@} contains the poles from input j to output i.
## In the SISO case, a single vector is accepted as well.
## @item k
## Matrix containing the gains for each channel.
## k(i,j) contains the gain from input j to output i.
## @item tsam
## Sampling time in seconds. If @var{tsam} is not specified,
## a continuous-time model is assumed.
## @item @dots{}
## Optional pairs of properties and values.
## Type @command{set (tf)} for more information.
## @end table
##
## @strong{Outputs}
## @table @var
## @item sys
## Transfer function model.
## @end table
##
## @seealso{tf, ss, dss, frd}
## @end deftypefn
## Author: Lukas Reichlin <lukas.reichlin@gmail.com>
## Created: September 2011
## Version: 0.2
function sys = zpk (varargin)
if (nargin <= 1) # zpk (), zpk (sys), zpk (k), zpk ('s')
sys = tf (varargin{:});
return;
elseif (nargin == 2 ...
&& ischar (varargin{1})) # zpk ('z', tsam)
sys = tf (varargin{:});
return;
endif
z = {}; p = {}; k = []; # default values
tsam = 0; # default sampling time
[mat_idx, opt_idx] = __lti_input_idx__ (varargin);
switch (numel (mat_idx))
case 1
k = varargin{mat_idx};
case 3
[z, p, k] = varargin{mat_idx};
case 4
[z, p, k, tsam] = varargin{mat_idx};
if (isempty (tsam) && is_real_matrix (tsam))
tsam = -1;
elseif (! issample (tsam, -10))
error ("zpk: invalid sampling time");
endif
case 0
## nothing to do here, just prevent case 'otherwise'
otherwise
print_usage ();
endswitch
varargin = varargin(opt_idx);
if (isempty (z) && isempty (p) && is_real_matrix (k))
sys = tf (k, varargin{:});
return;
endif
if (! iscell (z))
z = {z};
endif
if (! iscell (p))
p = {p};
endif
if (! size_equal (z, p, k))
error ("zpk: arguments 'z', 'p' and 'k' must have equal dimensions");
endif
## NOTE: accept [], scalars and vectors but not matrices as 'z' and 'p'
## because poly (matrix) returns the characteristic polynomial
## if the matrix is square!
if (! is_zp_vector (z{:}, 1)) # last argument 1 needed if z is empty cell
error ("zpk: first argument 'z' must be a vector or a cell of vectors");
endif
if (! is_zp_vector (p{:}, 1))
error ("zpk: second argument 'p' must be a vector or a cell of vectors")
endif
if (! is_real_matrix (k))
error ("zpk: third argument 'k' must be a real-valued gain matrix");
endif
num = cellfun (@(zer, gain) real (gain * poly (zer)), z, num2cell (k), "uniformoutput", false);
den = cellfun (@(pol) real (poly (pol)), p, "uniformoutput", false);
sys = tf (num, den, tsam, varargin{:});
endfunction
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