Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / control-2.3.52 / pzmap.m

diff --git a/octave_packages/control-2.3.52/pzmap.m b/octave_packages/control-2.3.52/pzmap.m
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+## Copyright (C) 2009   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} pzmap (@var{sys})
+## @deftypefnx {Function File} {[@var{p}, @var{z}] =} pzmap (@var{sys})
+## Plot the poles and zeros of an LTI system in the complex plane.
+## If no output arguments are given, the result is plotted on the screen.
+## Otherwise, the poles and zeros are computed and returned.
+##
+## @strong{Inputs}
+## @table @var
+## @item sys
+## LTI model.
+## @end table
+##
+## @strong{Outputs}
+## @table @var
+## @item p
+## Poles of @var{sys}.
+## @item z
+## Transmission zeros of @var{sys}.
+## @end table
+## @end deftypefn
+
+## Author: Lukas Reichlin <lukas.reichlin@gmail.com>
+## Created: November 2009
+## Version: 0.1
+
+function [pol_r, zer_r] = pzmap (sys)
+
+  ## TODO: multiplot feature:   pzmap (sys1, "b", sys2, "r", ...)
+
+  if (nargin != 1)
+    print_usage ();
+  endif
+
+  if (! isa (sys, "lti"))
+    error ("pzmap: argument must be an LTI system");
+  endif
+
+  pol = pole (sys);
+  zer = zero (sys);
+
+  if (! nargout)
+    pol_re = real (pol);
+    pol_im = imag (pol);
+    zer_re = real (zer);
+    zer_im = imag (zer);
+
+    plot (pol_re, pol_im, "xb", zer_re, zer_im, "or")
+    grid ("on")  
+    title (["Pole-Zero Map of ", inputname(1)])
+    xlabel ("Real Axis")
+    ylabel ("Imaginary Axis")
+  else
+    pol_r = pol;
+    zer_r = zer;
+  endif
+  
+endfunction