Add a useful package (from Source forge) for octave

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

diff --git a/octave_packages/control-2.3.52/@lti/tfdata.m b/octave_packages/control-2.3.52/@lti/tfdata.m
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+## Copyright (C) 2009, 2010, 2011, 2012   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{num}, @var{den}, @var{tsam}] =} tfdata (@var{sys})
+## @deftypefnx {Function File} {[@var{num}, @var{den}, @var{tsam}] =} tfdata (@var{sys}, @var{"vector"})
+## @deftypefnx {Function File} {[@var{num}, @var{den}, @var{tsam}] =} tfdata (@var{sys}, @var{"tfpoly"})
+## Access transfer function data.
+## Argument @var{sys} is not limited to transfer function models.
+## If @var{sys} is not a transfer function, it is converted automatically.
+##
+## @strong{Inputs}
+## @table @var
+## @item sys
+## Any type of LTI model.
+## @item "v", "vector"
+## For SISO models, return @var{num} and @var{den} directly as column vectors
+## instead of cells containing a single column vector.
+## @end table
+##
+## @strong{Outputs}
+## @table @var
+## @item num
+## Cell of numerator(s).  Each numerator is a row vector
+## containing the coefficients of the polynomial in descending powers of
+## the transfer function variable.
+## num@{i,j@} contains the numerator polynomial from input j to output i.
+## In the SISO case, a single vector is possible as well.
+## @item den
+## Cell of denominator(s).  Each denominator is a row vector
+## containing the coefficients of the polynomial in descending powers of
+## the transfer function variable.
+## den@{i,j@} contains the denominator polynomial from input j to output i.
+## In the SISO case, a single vector is possible as well.
+## @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 2009
+## Version: 0.5
+
+function [num, den, tsam] = tfdata (sys, rtype = "cell")
+
+  if (! isa (sys, "tf"))
+    sys = tf (sys);
+  endif
+
+  [num, den] = __sys_data__ (sys); 
+
+  tsam = sys.tsam;
+
+  if (! strncmpi (rtype, "t", 1))                # != tfpoly
+    num = cellfun (@get, num, "uniformoutput", false);
+    den = cellfun (@get, den, "uniformoutput", false);
+  endif
+
+  if (strncmpi (rtype, "v", 1) && issiso (sys))  # == vector
+    num = num{1};
+    den = den{1};
+  endif
+
+endfunction