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1 # Copyright (C) 1996,1998 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 function [num,den] = zp2tf(zer,pol,k) |
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20 # [num,den] = zp2tf(zer,pol,k) |
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21 # Converts zeros / poles to a transfer function. |
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22 # |
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23 # Inputs: |
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24 # zer, pol: vectors of (possibly complex) poles and zeros of a transfer |
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25 # function. Complex values should appear in conjugate pairs |
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26 # k: real scalar (leading coefficient) |
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27 # Forms the transfer function num/den from |
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28 # the vectors of poles and zeros. K is a scalar gain associated with the |
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29 # zeros. |
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30 |
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31 # Find out whether data was entered as a row or a column vector and |
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32 # convert to a column vector if necessary |
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33 # Written by A. S. Hodel with help from students Ingram, McGowan. |
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34 # a.s.hodel@eng.auburn.edu |
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35 # |
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36 |
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37 [rp,cp] = size(pol); |
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38 [rz,cz] = size(zer); |
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39 |
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40 if(!(is_vector(zer) | isempty(zer)) ) |
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41 error(sprintf("zer(%dx%d) must be a vector",rz,cz)); |
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42 elseif(!(is_vector(pol) | isempty(pol)) ) |
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43 error(sprintf("pol(%dx%d) must be a vector",rp,cp)); |
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44 elseif(length(zer) > length(pol)) |
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45 error(sprintf("zer(%dx%d) longer than pol(%dx%d)",rz,cz,rp,cp)); |
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46 endif |
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47 |
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48 num = k; den = 1; # initialize converted polynomials |
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49 |
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50 # call zp2ssg2 if there are complex conjugate pairs left, otherwise |
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51 # construct real zeros one by one. Repeat for poles. |
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52 while(!isempty(zer)) |
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53 if( max(abs(imag(zer))) ) [poly,zer] = zp2ssg2(zer); |
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54 else poly = [1 -zer(1)]; |
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55 zer = zer(2:length(zer)); endif |
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56 num = conv(num,poly); |
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57 endwhile |
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58 |
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59 while(!isempty(pol)) |
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60 if( max(abs(imag(pol))) ) [poly,pol] = zp2ssg2(pol); |
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61 else poly = [1 -pol(1)]; |
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62 pol = pol(2:length(pol)); endif |
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63 den = conv(den,poly); |
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64 endwhile |
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65 |
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66 endfunction |
