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1 ## Copyright (C) 1996 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{num}, @var{den}, @var{tsam}, @var{inname}, @var{outname}] =} sys2tf (@var{sys}) |
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21 ## Extract transfer function data from a system data structure |
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22 ## |
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23 ## See tf for parameter descriptions. |
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24 ## |
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25 ## @strong{Example} |
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26 ## @example |
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27 ## octave:1> sys=ss([1 -2; -1.1,-2.1],[0;1],[1 1]); |
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28 ## octave:2> [num,den] = sys2tf(sys) |
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29 ## num = 1.0000 -3.0000 |
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30 ## den = 1.0000 1.1000 -4.3000 |
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31 ## @end example |
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32 ## @end deftypefn |
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33 |
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34 ## Author: R. Bruce Tenison <btenison@eng.auburn.edu> |
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35 ## Created: June 24, 1994 |
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36 ## modified to make sys2tf by A. S. Hodel Aug 1995 |
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37 ## modified again for updated system format by John Ingram July 1996 |
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38 |
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39 function [num, den, tsam, inname, outname] = sys2tf (Asys) |
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40 |
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41 if(nargin != 1) |
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42 usage("[num,den,tsam,inname,outname] = sys2tf(Asys)"); |
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43 endif |
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44 |
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45 if( !isstruct(Asys)) |
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46 error("Asys must be a system data structure (see ss, tf, zp)"); |
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47 elseif (! is_siso(Asys) ) |
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48 [n, nz, m, p] = sysdimensions(Asys); |
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49 error(["system is not SISO (",num2str(m)," inputs, ... |
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50 ", num2str(p)," outputs"]); |
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51 endif |
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52 |
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53 Asys = sysupdate(Asys,"tf"); # just in case |
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54 |
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55 num = Asys.num; |
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56 den = Asys.den; |
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57 |
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58 tsam = sysgettsam(Asys); |
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59 inname = sysgetsignals(Asys,"in"); |
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60 outname = sysgetsignals(Asys,"out"); |
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61 |
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62 endfunction |
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63 |
