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1 ## Copyright (C) 1997 Kai P. Mueller |
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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} {} ctrb(@var{sys}, @var{b}) |
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21 ## @deftypefnx {Function File} {} ctrb(@var{A}, @var{B}) |
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22 ## Build controllability matrix |
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23 ## @example |
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24 ## 2 n-1 |
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25 ## Qs = [ B AB A B ... A B ] |
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26 ## @end example |
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27 ## |
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28 ## of a system data structure or the pair (@var{A}, @var{B}). |
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29 ## |
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30 ## @strong{Note} @code{ctrb} forms the controllability matrix. |
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31 ## The numerical properties of @code{is_controllable} |
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32 ## are much better for controllability tests. |
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33 ## @end deftypefn |
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34 |
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35 ## Author: Kai P. Mueller <mueller@ifr.ing.tu-bs.de> |
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36 ## Created: November 4, 1997 |
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37 ## based on is_controllable.m of Scottedward Hodel |
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38 |
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39 function Qs = ctrb (sys, b) |
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40 |
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41 if (nargin == 2) |
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42 a = sys; |
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43 elseif (nargin == 1 && is_struct(sys)) |
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44 sysupdate(sys,"ss"); |
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45 [a,b] = sys2ss(sys); |
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46 else |
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47 usage("ctrb(sys [, b])") |
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48 endif |
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49 |
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50 if (!is_abcd(a,b)) |
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51 Qs = []; |
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52 else |
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53 ## no need to check dimensions, we trust is_abcd(). |
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54 [na, ma] = size(a); |
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55 ## using imb avoids name conflict with the "mb" function |
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56 [inb, imb] = size(b); |
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57 Qs = zeros(na, ma*imb); |
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58 for i = 1:na |
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59 Qs(:, (i-1)*imb+1:i*imb) = b; |
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60 b = a * b; |
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61 endfor |
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62 endif |
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63 endfunction |
