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comparison scripts/signal/freqz_plot.m @ 18518:694e8f0b3862 stable

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freqz: Make frequency response plot visually compatible with Matlab (bug #41464) * freqz_plot.m: Eliminate the extraneous "pass band" subplot for visual compatibility with Matlab. Use y-axis labels instead of legends. Always autoscale the y-axis. Label the frequency axis in units of normalized radians or Hz depending on a new optional argument. * freqz.m: Tell freqz_plot whether the frequency vector is in normalized radians or Hz.
author Mike Miller <mtmiller@ieee.org>
date Thu, 13 Feb 2014 00:00:10 -0500
parents d63878346099
children 9d59bc3dc12d
comparison
equal deleted inserted replaced
18515:ff7e7928f160 18518:694e8f0b3862
15 ## You should have received a copy of the GNU General Public License 15 ## You should have received a copy of the GNU General Public License
16 ## along with Octave; see the file COPYING. If not, see 16 ## along with Octave; see the file COPYING. If not, see
17 ## <http://www.gnu.org/licenses/>. 17 ## <http://www.gnu.org/licenses/>.
18 18
19 ## -*- texinfo -*- 19 ## -*- texinfo -*-
20 ## @deftypefn {Function File} {} freqz_plot (@var{w}, @var{h}) 20 ## @deftypefn {Function File} {} freqz_plot (@var{w}, @var{h})
21 ## Plot the pass band, stop band and phase response of @var{h}. 21 ## @deftypefnx {Function File} {} freqz_plot (@var{w}, @var{h}, @var{freq_hz})
22 ## Plot the pass band, stop band and phase response of @var{h}. If the
23 ## optional @var{freq_norm} argument is true, the frequency vector @var{w}
24 ## is in units of normalized radians and the x-axis is labeled as such.
22 ## @end deftypefn 25 ## @end deftypefn
23 26
24 ## Author: Paul Kienzle <pkienzle@users.sf.net> 27 ## Author: Paul Kienzle <pkienzle@users.sf.net>
25 28
26 function freqz_plot (w, h) 29 function freqz_plot (w, h, freq_norm = false)
27 30
28 if (nargin != 2) 31 if (nargin < 2 || nargin > 3)
29 print_usage (); 32 print_usage ();
30 endif 33 endif
31 34
32 n = length (w); 35 n = length (w);
33 36
36 ## w = w (2 : length (w)); 39 ## w = w (2 : length (w));
37 ## n = n-1; 40 ## n = n-1;
38 41
39 mag = 20 * log10 (abs (h)); 42 mag = 20 * log10 (abs (h));
40 phase = unwrap (arg (h)); 43 phase = unwrap (arg (h));
41 maxmag = max (mag);
42 44
43 subplot (3, 1, 1); 45 if (freq_norm)
46 x_label = "Normalized Frequency (\\times\\pi rad/sample)";
47 else
48 x_label = "Frequency (Hz)";
49 endif
50
51 subplot (2, 1, 1);
44 plot (w, mag); 52 plot (w, mag);
45 grid ("on"); 53 grid ("on");
46 legend ("Pass band (dB)"); 54 axis ([w(1), w(n)], "autoy");
47 axis ([w(1), w(n), maxmag-3, maxmag], "labely"); 55 xlabel (x_label);
56 ylabel ("Magnitude (dB)");
48 57
49 subplot (3, 1, 2); 58 subplot (2, 1, 2);
50 plot (w, mag);
51 grid ("on");
52 legend ("Stop band (dB)");
53 if (maxmag - min (mag) > 100)
54 axis ([w(1), w(n), maxmag-100, maxmag], "labely");
55 else
56 axis ("autoy", "labely");
57 endif
58
59 subplot (3, 1, 3);
60 plot (w, phase*360/(2*pi)); 59 plot (w, phase*360/(2*pi));
61 grid ("on"); 60 grid ("on");
62 legend ("Phase (degrees)"); 61 axis ([w(1), w(n)], "autoy");
63 xlabel ("Frequency"); 62 xlabel (x_label);
64 axis ([w(1), w(n)], "autoy", "label"); 63 ylabel ("Phase (degrees)");
65 64
66 endfunction 65 endfunction
67 66