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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 } { outputs =} ss2zp ( inputs ) |
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21 ## @format |
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22 ## Converts a state space representation to a set of poles and zeros. |
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23 ## |
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24 ## [pol,zer,k] = ss2zp(a,b,c,d) returns the poles and zeros of the state space |
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25 ## system (a,b,c,d). K is a gain associated with the zeros. |
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26 ## |
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27 ## used internally in system data structure format manipulations |
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28 ## |
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29 ## |
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30 ## @end format |
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31 ## @end deftypefn |
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32 |
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33 |
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34 function [zer,pol,k] = ss2zp(a,b,c,d) |
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35 |
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36 ## Written by David Clem August 15, 1994 |
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37 ## Hodel: changed order of output arguments to zer, pol, k. July 1996 |
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38 ## a s hodel: added argument checking, allow for pure gain blocks aug 1996 |
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39 |
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40 if(nargin != 4) |
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41 usage("[zer,pol,k] = ss2zp(a,b,c,d)"); |
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42 endif |
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43 |
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44 [n,m,p] = abcddim(a,b,c,d); |
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45 if (n == -1) |
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46 error("ss2tf: Non compatible matrix arguments"); |
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47 elseif ( (m != 1) | (p != 1)) |
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48 error(["ss2tf: not SISO system: m=",num2str(m)," p=",num2str(p)]); |
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49 endif |
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50 |
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51 if(n == 0) |
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52 ## gain block only |
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53 k = d; |
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54 zer = pol = []; |
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55 else |
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56 ## First, get the denominator coefficients |
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57 [zer,k] = tzero(a,b,c,d); |
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58 pol = eig(a); |
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59 endif |
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60 endfunction |
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61 |
