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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 function outsys = tf2sys(num,den,tsam,inname,outname) |
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20 # |
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21 # sys = tf2sys(num,den{,tsam,inname,outname}) |
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22 # build system data structure from transfer function format data |
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23 # inputs: |
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24 # num, den: coefficients of numerator/denominator polynomials |
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25 # tsam: sampling interval. default: 0 (continuous time) |
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26 # inname, outname: input/output signal names (string variables) |
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27 # outputs: sys = system data structure |
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28 |
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29 # Written by R. Bruce Tenison July 29, 1994 |
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30 # Name changed to TF2SYS July 1995 |
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31 # updated for new system data structure format July 1996 |
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32 |
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33 save_val = implicit_str_to_num_ok; |
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34 implicit_str_to_num_ok = 1; |
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35 |
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36 # Test for the correct number of input arguments |
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37 if ((nargin < 2) || (nargin > 5)) |
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38 usage('outsys=tf2sys(num,den[,tsam,inname,outname])'); |
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39 return |
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40 endif |
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41 |
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42 # check input format |
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43 if( ! ( (is_vector(num) || is_scalar(num)) && ... |
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44 (is_vector(den) || is_scalar(den))) ) |
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45 error(['num (',num2str(rows(num)),'x',num2str(columns(num)), ... |
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46 ') and den (',num2str(rows(den)),'x',num2str(columns(den)), ... |
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47 ') must be vectors']) |
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48 endif |
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49 |
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50 # strip leading zero coefficients |
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51 num = tf2sysl(num); |
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52 den = tf2sysl(den); |
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53 |
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54 if (length(num) > length(den)) |
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55 error("# of poles (%d) < # of zeros (%d)",length(den)-1, length(num)-1); |
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56 endif |
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57 |
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58 # check sampling interval (if any) |
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59 if(nargin <= 2) tsam = 0; # default |
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60 elseif (isempty(tsam)) tsam = 0; endif |
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61 if ( (! (is_scalar(tsam) && (imag(tsam) == 0) )) || (tsam < 0) ) |
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62 error('tsam must be a positive real scalar') |
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63 endif |
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64 |
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65 outsys.num = num; |
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66 outsys.den = den; |
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67 |
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68 # Set the system vector: active = 0(tf), updated = [1 0 0]; |
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69 outsys.sys = [0, 1, 0, 0]; |
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70 |
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71 # Set defaults |
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72 outsys.tsam = tsam; |
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73 outsys.n = length(den)-1; |
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74 outsys.nz = 0; |
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75 outsys.yd = 0; # assume discrete-time |
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76 # check discrete time |
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77 if(tsam > 0) |
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78 [outsys.n,outsys.nz] = swap(outsys.n, outsys.nz); |
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79 outsys.yd = 1; |
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80 endif |
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81 |
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82 outsys.inname = sysdefioname(1,"u"); |
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83 outsys.outname = sysdefioname(1,"y"); |
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84 outsys.stname = sysdefstname(outsys.n,outsys.nz); |
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85 |
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86 # Set name of input |
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87 if (nargin > 3) |
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88 # make sure its a list of a single string |
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89 if(!isempty(inname)) |
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90 if(!is_list(inname)) inname = list(inname); endif |
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91 if( !is_signal_list(inname) ) |
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92 error("inname must be a string or list of strings"); |
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93 endif |
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94 if(length(inname) > 1) |
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95 warning("tf2sys: %d input names provided; first used",length(inname)); |
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96 inname = inname(1); |
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97 endif |
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98 outsys = syssetsignals(outsys,"in",inname); |
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99 endif |
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100 endif |
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101 |
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102 # Set name of output |
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103 if (nargin > 4) |
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104 if(!isempty(outname)) |
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105 if(!is_list(outname)) outname = list(outname); endif |
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106 if(!is_signal_list(outname)) |
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107 error("outname must be a string or a list of strings"); |
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108 endif |
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109 if(length(outname) > 1) |
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110 warning("tf2sys: %d output names provided; first used",length(outname)); |
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111 outname = outname(1); |
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112 endif |
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113 outsys = syssetsignals(outsys,"out",outname); |
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114 endif |
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115 endif |
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116 |
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117 implicit_str_to_num_ok = save_val; |
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118 endfunction |
