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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} {[@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 [10^wmin,10^wmax] |
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24 ## |
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25 ## Used internally in freqresp (@code{bode}, @code{nyquist}) |
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26 ## @end deftypefn |
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27 |
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28 function [wmin, wmax] = bode_bounds (zer, pol, DIGITAL, tsam) |
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29 |
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30 ## make sure zer,pol are row vectors |
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31 if(!isempty(pol)) pol = reshape(pol,1,length(pol)); endif |
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32 if(!isempty(zer)) zer = reshape(zer,1,length(zer)); endif |
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33 |
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34 ## check for natural frequencies away from omega = 0 |
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35 if (DIGITAL) |
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36 ## The 2nd conditions prevents log(0) in the next log command |
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37 iiz = find(abs(zer - 1) > norm(zer) * eps && abs(zer) > norm(zer) * eps); |
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38 iip = find(abs(pol - 1) > norm(pol) * eps && abs(pol) > norm(pol) * eps); |
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39 |
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40 ## avoid dividing empty matrices, it would work but looks nasty |
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41 if (!isempty(iiz)) czer = log(zer(iiz))/tsam; |
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42 else czer = []; endif |
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43 |
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44 if (!isempty(iip)) cpol = log(pol(iip))/tsam; |
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45 else cpol = []; endif |
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46 |
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47 else |
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48 ## continuous |
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49 iip = find((abs(pol)) > (norm(pol) * eps)); |
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50 iiz = find((abs(zer)) > (norm(zer) * eps)); |
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51 |
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52 if(!isempty(zer)) czer = zer(iiz); |
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53 else czer = []; endif |
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54 if(!isempty(pol)) cpol = pol(iip); |
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55 else cpol = []; endif |
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56 endif |
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57 |
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58 if(max(size(iip)) + max(size(iiz)) ) |
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59 wmin = floor(log10(min(abs([cpol,czer])))); |
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60 wmax = ceil(log10(max(abs([cpol,czer])))); |
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61 else |
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62 ## no poles/zeros away from omega = 0; pick defaults |
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63 wmin = -1; |
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64 wmax = 3; |
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65 endif |
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66 |
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67 ## expand to show the entirety of the "interesting" portion of the plot |
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68 wmin--; |
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69 wmax++; |
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70 |
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71 ## run digital frequency all the way to pi |
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72 if (DIGITAL) wmax = log10(pi/tsam); endif |
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73 |
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74 endfunction |
