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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{c}, @var{tsam}, @var{input}, @var{output}] =} sys2fir (@var{sys}) |
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21 ## |
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22 ## Extract FIR data from system data structure; see @ref{fir2sys} for |
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23 ## parameter descriptions. |
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24 ## @end deftypefn |
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25 ## @seealso{fir2sys} |
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26 |
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27 ## Author: A. S. Hodel <a.s.hodel@eng.auburn.edu> |
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28 ## Created: July 1996 |
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29 |
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30 function [c, tsam, inname, outname] = sys2fir (sys) |
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31 |
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32 ## let sys2tf do most of the work |
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33 |
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34 [num,den,tsam,inname,outname] = sys2tf(sys); |
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35 |
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36 alph = den(1); # scale to get monic denominator |
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37 den = den/alph; |
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38 num = num/alph; |
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39 l = length(den); |
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40 m = length(num); |
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41 if( norm(den(2:l)) ) |
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42 sysout(sys,"tf"); |
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43 error("denominator has poles away from origin"); |
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44 elseif( !is_digital(sys) ) |
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45 error("system must be discrete-time to be FIR"); |
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46 elseif(m != l) |
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47 warning(["sys2fir: deg(num) - deg(den) = ",num2str(m-l), ... |
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48 "; coefficients must be shifted"]); |
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49 endif |
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50 c = num; |
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51 endfunction |
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52 |