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1 ## Copyright (C) 1996, 1999, 2000, 2004, 2005, 2006, 2007 |
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2 ## Auburn University. All rights reserved. |
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3 ## |
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4 ## This file is part of Octave. |
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5 ## |
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6 ## Octave is free software; you can redistribute it and/or modify it |
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7 ## under the terms of the GNU General Public License as published by |
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8 ## the Free Software Foundation; either version 3 of the License, or (at |
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9 ## your option) any later version. |
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10 ## |
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11 ## Octave is distributed in the hope that it will be useful, but |
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12 ## WITHOUT ANY WARRANTY; without even the implied warranty of |
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13 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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14 ## General Public License for more details. |
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15 ## |
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16 ## You should have received a copy of the GNU General Public License |
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17 ## along with Octave; see the file COPYING. If not, see |
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18 ## <http://www.gnu.org/licenses/>. |
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19 |
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20 ## -*- texinfo -*- |
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21 ## @deftypefn {Function File} {@var{digital} =} is_digital (@var{sys}, @var{eflg}) |
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22 ## Return nonzero if system is digital. |
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23 ## |
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24 ## @strong{Inputs} |
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25 ## @table @var |
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26 ## @item sys |
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27 ## System data structure. |
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28 ## @item eflg |
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29 ## When equal to 0 (default value), exits with an error if the system |
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30 ## is mixed (continuous and discrete components); when equal to 1, print |
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31 ## a warning if the system is mixed (continuous and discrete); when equal |
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32 ## to 2, operate silently. |
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33 ## @end table |
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34 ## |
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35 ## @strong{Output} |
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36 ## @table @var |
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37 ## @item digital |
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38 ## When equal to 0, the system is purely continuous; when equal to 1, the |
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39 ## system is purely discrete; when equal to -1, the system is mixed continuous |
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40 ## and discrete. |
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41 ## @end table |
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42 ## Exits with an error if @var{sys} is a mixed (continuous and discrete) system. |
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43 ## @end deftypefn |
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44 |
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45 ## Author: A. S. Hodel <a.s.hodel@eng.auburn.edu> |
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46 ## Created: July 1996 |
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47 |
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48 function DIGITAL = is_digital (sys, eflg) |
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49 |
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50 switch (nargin) |
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51 case 1 |
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52 eflg = 0; |
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53 case 2 |
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54 if (isempty (find (eflg == [0, 1, 2]))) |
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55 error ("invalid value of eflg=%g", eflg); |
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56 endif |
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57 otherwise, |
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58 print_usage (); |
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59 endswitch |
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60 |
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61 ## checked for sampled data system (mixed) |
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62 ## discrete system |
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63 sysyd = sysgetsignals (sys, "yd"); |
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64 [nn, nz] = sysdimensions (sys); |
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65 cont = sum (sysyd == 0) + nn; |
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66 tsam = sysgettsam (sys); |
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67 dig = sum (sysyd != 0) + nz + tsam; |
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68 |
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69 ## check for mixed system |
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70 if (cont*dig != 0) |
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71 switch (eflg) |
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72 case 0 |
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73 error ("continuous/discrete system; use syscont, sysdisc, or c2d first"); |
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74 case 1 |
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75 warning ("is_digital: mixed continuous/discrete system"); |
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76 endswitch |
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77 dig_sign = -1; |
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78 else |
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79 dig_sign = 1; |
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80 endif |
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81 |
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82 DIGITAL = dig_sign*(tsam > 0); |
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83 |
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84 endfunction |
