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1 ## Copyright (C) 1993, 1994, 1995 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{retval} =} is_detectable (@var{a}, @var{c}, @var{tol}, @var{dflg}) |
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21 ## @deftypefnx {Function File} {@var{retval} =} is_detectable (@var{sys}, @var{tol}) |
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22 ## Test for detactability (observability of unstable modes) of (@var{a},@var{c}). |
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23 ## |
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24 ## Returns 1 if the system @var{a} or the pair (@var{a},@var{c})is |
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25 ## detectable, 0 if not, and -1 if the system has unobservable modes at the |
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26 ## imaginary axis (unit circle for discrete-time systems) |
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27 ## |
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28 ## @strong{See} @code{is_stabilizable} for detailed description of |
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29 ## arguments and computational method. |
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30 ## |
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31 ## |
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32 ## @end deftypefn |
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33 ## @seealso{is_stabilizable, size, rows, columns, length, ismatrix, |
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34 ## isscalar, and isvector} |
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35 |
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36 ## Author: A. S. Hodel <a.s.hodel@eng.auburn.edu> |
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37 ## Created: August 1993 |
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38 ## Updated by John Ingram (ingraje@eng.auburn.edu) July 1996. |
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39 |
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40 function [retval, U] = is_detectable (a, c, tol, dflg) |
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41 |
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42 if( nargin < 1) |
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43 usage("retval = is_detectable(a , {c , tol, dlfg})"); |
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44 elseif(isstruct(a)) |
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45 ## system form |
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46 if(nargin == 2) |
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47 tol = c; |
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48 elseif(nargin > 2) |
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49 usage("retval = is_detectable(sys {, tol})"); |
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50 endif |
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51 dflg = is_digital(a); |
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52 [a,b,c] = sys2ss(a); |
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53 else |
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54 if ((nargin > 4)||(nargin == 1)) |
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55 usage("retval = is_detectable(a , {c , tol, dflg})"); |
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56 endif |
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57 if (~exist("dflg")) |
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58 dflg = 0; |
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59 end |
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60 end |
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61 |
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62 if(~exist("tol")) |
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63 tol = 200*eps; |
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64 end |
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65 retval = is_stabilizable(a',c',tol,dflg); |
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66 |
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67 endfunction |
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68 |
