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1 ## Copyright (C) 1996, 1998 Auburn University. All rights reserved. |
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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 the |
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7 ## Free Software Foundation; either version 2, or (at your option) any |
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8 ## later version. |
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9 ## |
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10 ## Octave is distributed in the hope that it will be useful, but WITHOUT |
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11 ## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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12 ## FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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13 ## 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, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
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18 ## 02110-1301 USA. |
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19 |
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20 ## -*- texinfo -*- |
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21 ## @deftypefn {Function File} {} fir2sys (@var{num}, @var{tsam}, @var{inname}, @var{outname}) |
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22 ## construct a system data structure from @acronym{FIR} description |
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23 ## |
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24 ## @strong{Inputs} |
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25 ## @table @var |
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26 ## @item num |
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27 ## vector of coefficients |
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28 ## @ifinfo |
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29 ## [c0, c1, ..., cn] |
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30 ## @end ifinfo |
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31 ## @iftex |
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32 ## @tex |
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33 ## $ [c_0, c_1, \ldots, c_n ]$ |
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34 ## @end tex |
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35 ## @end iftex |
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36 ## of the @acronym{SISO} @acronym{FIR} transfer function |
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37 ## @ifinfo |
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38 ## C(z) = c0 + c1*z^(-1) + c2*z^(-2) + ... + cn*z^(-n) |
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39 ## @end ifinfo |
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40 ## @iftex |
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41 ## @tex |
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42 ## $$ C(z) = c_0 + c_1z^{-1} + c_2z^{-2} + \ldots + c_nz^{-n} $$ |
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43 ## @end tex |
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44 ## @end iftex |
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45 ## |
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46 ## @item tsam |
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47 ## sampling time (default: 1) |
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48 ## |
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49 ## @item inname |
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50 ## name of input signal; may be a string or a list with a single entry. |
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51 ## |
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52 ## @item outname |
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53 ## name of output signal; may be a string or a list with a single entry. |
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54 ## @end table |
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55 ## |
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56 ## @strong{Output} |
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57 ## @table @var |
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58 ## @item sys |
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59 ## system data structure |
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60 ## @end table |
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61 ## |
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62 ## @strong{Example} |
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63 ## @example |
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64 ## octave:1> sys = fir2sys([1 -1 2 4],0.342,\ |
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65 ## > "A/D input","filter output"); |
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66 ## octave:2> sysout(sys) |
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67 ## Input(s) |
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68 ## 1: A/D input |
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69 ## |
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70 ## Output(s): |
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71 ## 1: filter output (discrete) |
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72 ## |
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73 ## Sampling interval: 0.342 |
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74 ## transfer function form: |
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75 ## 1*z^3 - 1*z^2 + 2*z^1 + 4 |
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76 ## ------------------------- |
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77 ## 1*z^3 + 0*z^2 + 0*z^1 + 0 |
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78 ## @end example |
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79 ## @end deftypefn |
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80 |
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81 ## Author: R. Bruce Tenison <btenison@eng.auburn.edu> |
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82 ## Created: July 29, 1994 |
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83 ## Name changed to TF2SYS July 1995 |
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84 ## updated for new system data structure format July 1996 |
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85 ## adapted from tf2sys july 1996 |
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86 |
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87 function sys = fir2sys (num, tsam, inname, outname) |
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88 |
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89 ## Test for the correct number of input arguments |
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90 if (nargin < 1 | nargin > 4) |
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91 usage ("sys = fir2sys(num [, tsam, inname, outname])"); |
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92 endif |
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93 |
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94 ## let tf do the argument checking |
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95 den = [1,zeros(1,length(num)-1)]; |
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96 |
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97 ## check sampling interval (if any) |
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98 if (nargin <= 1) |
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99 tsam = 1; # default |
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100 elseif (isempty(tsam)) |
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101 tsam = 1; |
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102 endif |
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103 |
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104 ## Set name of input |
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105 if (nargin < 3) |
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106 inname = __sysdefioname__ (1, "u"); |
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107 endif |
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108 |
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109 ## Set name of output |
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110 if (nargin < 4) |
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111 outname = __sysdefioname__ (1, "y"); |
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112 endif |
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113 |
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114 sys = tf (num, den, tsam, inname, outname); |
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115 |
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116 endfunction |
