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1 ## Copyright (C) 2002 John W. Eaton |
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2 ## |
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3 ## This file is part of Octave. |
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4 ## |
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5 ## Octave is free software; you can redistribute it and/or modify it |
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6 ## under the terms of the GNU General Public License as published by |
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7 ## the Free Software Foundation; either version 2, or (at your option) |
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8 ## any later version. |
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9 ## |
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10 ## Octave is distributed in the hope that it will be useful, but |
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11 ## WITHOUT ANY WARRANTY; without even the implied warranty of |
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12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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13 ## General Public License for more details. |
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14 ## |
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15 ## You should have received a copy of the GNU General Public License |
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16 ## along with Octave; see the file COPYING. If not, write to the Free |
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17 ## Software Foundation, 59 Temple Place - Suite 330, Boston, MA |
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18 ## 02111-1307, USA. |
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19 |
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20 ## -*- texinfo -*- |
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21 ## @deftypefn {Function File} freqz_plot (@var{w}, @var{h}) |
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22 ## Plot the pass band, stop band and phase response of @var{h}. |
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23 ## @end deftypefn |
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24 |
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25 ## Author: Paul Kienzle <pkienzle@users.sf.net> |
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26 |
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27 function freqz_plot(w,h) |
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28 |
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29 n = length (w); |
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30 |
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31 ## ## exclude zero-frequency |
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32 ## h = h (2 : length (h)); |
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33 ## w = w (2 : length (w)); |
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34 ## n = n-1; |
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35 |
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36 mag = 20 * log10 (abs (h)); |
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37 phase = unwrap (arg (h)); |
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38 maxmag = max (mag); |
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39 |
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40 unwind_protect |
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41 |
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42 ## Protect graph state. |
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43 |
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44 subplot (311); |
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45 gset lmargin 10; |
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46 axis ("labely"); |
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47 xlabel (""); |
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48 grid ("on"); |
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49 axis ([ w(1), w(n), maxmag-3, maxmag ]); |
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50 plot (w, mag, ";Pass band (dB);"); |
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51 |
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52 subplot (312); |
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53 axis ("labely"); |
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54 title (""); |
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55 xlabel (""); |
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56 gset tmargin 0; |
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57 grid ("on"); |
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58 if (maxmag - min (mag) > 100) |
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59 axis ([ w(1), w(n), maxmag-100, maxmag ]); |
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60 else |
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61 axis ("autoy"); |
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62 endif |
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63 plot (w, mag, ";Stop band (dB);"); |
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64 |
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65 subplot (313); |
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66 axis ("label"); |
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67 title (""); |
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68 grid ("on"); |
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69 axis ("autoy"); |
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70 xlabel ("Frequency"); |
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71 axis ([ w(1), w(n) ]); |
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72 plot (w, phase*360/(2*pi), ";Phase (degrees);"); |
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73 |
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74 unwind_protect_cleanup |
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75 |
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76 ## Restore graph state. |
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77 |
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78 ## XXX FIXME XXX -- if automatic_replot is non-zero, this will |
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79 ## mess up the graph, however if we don't do it here then the user |
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80 ## will have to do it themselves. |
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81 |
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82 grid ("off"); |
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83 axis ("auto", "label"); |
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84 gset lmargin; |
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85 gset tmargin; |
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86 oneplot (); |
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87 |
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88 end_unwind_protect |
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89 |
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90 endfunction |
