Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / control-2.3.52 / @lti / zpkdata.m

diff --git a/octave_packages/control-2.3.52/@lti/zpkdata.m b/octave_packages/control-2.3.52/@lti/zpkdata.m
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+## Copyright (C) 2011   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{z}, @var{p}, @var{k}, @var{tsam}] =} zpkdata (@var{sys})
+## @deftypefnx {Function File} {[@var{z}, @var{p}, @var{k}, @var{tsam}] =} zpkdata (@var{sys}, @var{"v"})
+## Access zero-pole-gain data.
+##
+## @strong{Inputs}
+## @table @var
+## @item sys
+## Any type of LTI model.
+## @item "v", "vector"
+## For SISO models, return @var{z} and @var{p} directly as column vectors
+## instead of cells containing a single column vector.
+## @end table
+##
+## @strong{Outputs}
+## @table @var
+## @item z
+## Cell of column vectors containing the zeros for each channel.
+## z@{i,j@} contains the zeros from input j to output i.
+## @item p
+## Cell of column vectors containing the poles for each channel.
+## p@{i,j@} contains the poles from input j to output i.
+## @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{sys} is a continuous-time model,
+## a zero is returned.
+## @end table
+## @end deftypefn
+
+## Author: Lukas Reichlin <lukas.reichlin@gmail.com>
+## Created: September 2011
+## Version: 0.1
+
+function [z, p, k, tsam] = zpkdata (sys, rtype = "cell")
+
+  [num, den, tsam] = tfdata (sys);
+
+  z = cellfun (@roots, num, "uniformoutput", false);
+  p = cellfun (@roots, den, "uniformoutput", false);
+  k = cellfun (@(n,d) n(1)/d(1), num, den);
+
+  if (strncmpi (rtype, "v", 1) && issiso (sys))
+    z = z{1};
+    p = p{1};
+  endif
+
+endfunction