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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 |
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7 ## the Free Software Foundation; either version 3 of the License, or (at |
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8 ## your option) any later version. |
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9 ## |
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10 ## Octave is distributed in the hope that it will be useful, but |
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11 ## WITHOUT ANY WARRANTY; without even the implied warranty of |
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12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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13 ## General Public License 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, see |
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17 ## <http://www.gnu.org/licenses/>. |
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18 |
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19 ## -*- texinfo -*- |
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20 ## @deftypefn {Function File} {[@var{wmin}, @var{wmax}] =} bode_bounds (@var{zer}, @var{pol}, @var{dflg}, @var{tsam}) |
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21 ## Get default range of frequencies based on cutoff frequencies of system |
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22 ## poles and zeros. |
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23 ## Frequency range is the interval |
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24 ## @iftex |
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25 ## @tex |
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26 ## $ [ 10^{w_{min}}, 10^{w_{max}} ] $ |
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27 ## @end tex |
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28 ## @end iftex |
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29 ## @ifinfo |
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30 ## [10^@var{wmin}, 10^@var{wmax}] |
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31 ## @end ifinfo |
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32 ## |
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33 ## Used internally in @command{__freqresp__} (@command{bode}, @command{nyquist}) |
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34 ## @end deftypefn |
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35 |
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36 function [wmin, wmax] = bode_bounds (zer, pol, DIGITAL, tsam) |
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37 |
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38 ## make sure zer,pol are row vectors |
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39 if(!isempty(pol)) pol = reshape(pol,1,length(pol)); endif |
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40 if(!isempty(zer)) zer = reshape(zer,1,length(zer)); endif |
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41 |
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42 ## check for natural frequencies away from omega = 0 |
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43 if (DIGITAL) |
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44 ## The 2nd conditions prevents log(0) in the next log command |
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45 iiz = find(abs(zer - 1) > norm(zer) * eps && abs(zer) > norm(zer) * eps); |
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46 iip = find(abs(pol - 1) > norm(pol) * eps && abs(pol) > norm(pol) * eps); |
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47 |
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48 ## avoid dividing empty matrices, it would work but looks nasty |
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49 if (!isempty(iiz)) czer = log(zer(iiz))/tsam; |
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50 else czer = []; endif |
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51 |
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52 if (!isempty(iip)) cpol = log(pol(iip))/tsam; |
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53 else cpol = []; endif |
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54 |
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55 else |
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56 ## continuous |
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57 iip = find((abs(pol)) > (norm(pol) * eps)); |
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58 iiz = find((abs(zer)) > (norm(zer) * eps)); |
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59 |
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60 if(!isempty(zer)) czer = zer(iiz); |
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61 else czer = []; endif |
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62 if(!isempty(pol)) cpol = pol(iip); |
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63 else cpol = []; endif |
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64 endif |
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65 |
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66 if (isempty (iip) && isempty (iiz)) |
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67 ## no poles/zeros away from omega = 0; pick defaults |
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68 wmin = -1; |
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69 wmax = 3; |
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70 else |
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71 wmin = floor(log10(min(abs([cpol,czer])))); |
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72 wmax = ceil(log10(max(abs([cpol,czer])))); |
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73 endif |
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74 |
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75 ## expand to show the entirety of the "interesting" portion of the plot |
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76 wmin--; |
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77 wmax++; |
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78 |
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79 ## run digital frequency all the way to pi |
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80 if (DIGITAL) wmax = log10(pi/tsam); endif |
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81 |
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82 endfunction |
