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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, 59 Temple Place, Suite 330, Boston, MA 02111 USA. |
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18 |
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19 ## -*- texinfo -*- |
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20 ## @deftypefn {Function File } { @var{sys} =} fir2sys ( @var{num}@{, @var{tsam}, @var{inname}, @var{outname} @} ) |
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21 ## construct a system data structure from FIR description |
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22 ## |
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23 ## @strong{Inputs:} |
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24 ## @table @var |
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25 ## @item num |
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26 ## vector of coefficients @math{[c_0 c_1 ... c_n]} |
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27 ## of the SISO FIR transfer function |
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28 ## @ifinfo |
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29 ## |
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30 ## C(z) = c0 + c1*z^@{-1@} + c2*z^@{-2@} + ... + znz^@{-n@} |
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31 ## |
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32 ## @end ifinfo |
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33 ## @iftex |
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34 ## @tex |
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35 ## $$C(z) = c0 + c1*z^{-1} + c2*z^{-2} + ... + znz^{-n}$$ |
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36 ## @end tex |
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37 ## @end iftex |
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38 ## |
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39 ## @item tsam |
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40 ## sampling time (default: 1) |
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41 ## |
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42 ## @item inname |
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43 ## name of input signal; may be a string or a list with a single entry. |
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44 ## |
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45 ## @item outname |
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46 ## name of output signal; may be a string or a list with a single entry. |
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47 ## @end table |
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48 ## |
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49 ## @strong{Outputs} |
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50 ## @var{sys} (system data structure) |
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51 ## |
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52 ## @strong{Example} |
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53 ## @example |
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54 ## octave:1> sys = fir2sys([1 -1 2 4],0.342,"A/D input","filter output"); |
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55 ## octave:2> sysout(sys) |
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56 ## Input(s) |
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57 ## 1: A/D input |
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58 ## |
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59 ## Output(s): |
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60 ## 1: filter output (discrete) |
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61 ## |
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62 ## Sampling interval: 0.342 |
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63 ## transfer function form: |
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64 ## 1*z^3 - 1*z^2 + 2*z^1 + 4 |
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65 ## ------------------------- |
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66 ## 1*z^3 + 0*z^2 + 0*z^1 + 0 |
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67 ## @end example |
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68 ## @end deftypefn |
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69 |
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70 function sys = fir2sys (num,tsam,inname,outname) |
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71 |
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72 ## Written by R. Bruce Tenison July 29, 1994 |
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73 ## Name changed to TF2SYS July 1995 |
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74 ## updated for new system data structure format July 1996 |
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75 ## adapted from tf2sys july 1996 |
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76 |
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77 ## Test for the correct number of input arguments |
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78 if (nargin < 1 | nargin > 4) |
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79 usage('sys=fir2sys(num[,tsam,inname,outname])'); |
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80 endif |
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81 |
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82 ## let tf2sys do the argument checking |
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83 den = [1,zeros(1,length(num)-1)]; |
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84 |
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85 ## check sampling interval (if any) |
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86 if(nargin <= 1) tsam = 1; # default |
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87 elseif (isempty(tsam)) tsam = 1; endif |
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88 |
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89 ## Set name of input |
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90 if(nargin < 3) inname = sysdefioname(1,"u"); endif |
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91 |
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92 ## Set name of output |
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93 if(nargin < 4) outname = sysdefioname(1,"y"); endif |
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94 |
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95 sys = tf2sys(num,den,tsam,inname,outname); |
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96 |
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97 endfunction |
