update packages

[CreaPhase.git] / octave_packages / m / signal / freqz_plot.m

diff --git a/octave_packages/m/signal/freqz_plot.m b/octave_packages/m/signal/freqz_plot.m
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+++ b/octave_packages/m/signal/freqz_plot.m
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+## Copyright (C) 2002-2012 John W. Eaton
+##
+## This file is part of Octave.
+##
+## Octave 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.
+##
+## Octave 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 Octave; see the file COPYING.  If not, see
+## <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {} freqz_plot (@var{w}, @var{h})
+## Plot the pass band, stop band and phase response of @var{h}.
+## @end deftypefn
+
+## Author: Paul Kienzle <pkienzle@users.sf.net>
+
+function freqz_plot (w, h)
+
+  if (nargin != 2)
+    print_usage ();
+  endif
+
+  n = length (w);
+
+  ## ## exclude zero-frequency
+  ## h = h (2 : length (h));
+  ## w = w (2 : length (w));
+  ## n = n-1;
+
+  mag = 20 * log10 (abs (h));
+  phase = unwrap (arg (h));
+  maxmag = max (mag);
+
+  subplot (3, 1, 1);
+  plot (w, mag);
+  grid ("on");
+  legend ("Pass band (dB)");
+  axis ([w(1), w(n), maxmag-3, maxmag], "labely");
+
+  subplot (3, 1, 2);
+  plot (w, mag);
+  grid ("on");
+  legend ("Stop band (dB)");
+  if (maxmag - min (mag) > 100)
+    axis ([w(1), w(n), maxmag-100, maxmag], "labely");
+  else
+    axis ("autoy", "labely");
+  endif
+
+  subplot (3, 1, 3);
+  plot (w, phase*360/(2*pi));
+  grid ("on");
+  legend ("Phase (degrees)");
+  xlabel ("Frequency");
+  axis ([w(1), w(n)], "autoy", "label");
+
+endfunction