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1 ## Copyright (C) 1996, 1997 John W. Eaton |
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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 2, or (at your option) |
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8 ## 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, write to the Free |
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17 ## Software Foundation, 59 Temple Place - Suite 330, Boston, MA |
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18 ## 02111-1307, USA. |
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19 |
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20 ## -*- texinfo -*- |
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21 ## @deftypefn {Function File} {} polyderiv (@var{c}) |
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22 ## Return the coefficients of the derivative of the polynomial whose |
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23 ## coefficients are given by vector @var{c}. |
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24 ## @end deftypefn |
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25 |
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26 ## SEE ALSO: poly, polyinteg, polyreduce, roots, conv, deconv, residue, |
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27 ## filter, polyval, polyvalm |
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28 |
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29 ## Author: Tony Richardson <arichard@stark.cc.oh.us> |
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30 ## Created: June 1994 |
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31 ## Adapted-By: jwe |
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32 |
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33 function q = polyderiv (p) |
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34 |
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35 if (nargin != 1) |
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36 usage ("polyderiv (vector)"); |
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37 endif |
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38 |
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39 if (! is_vector (p)) |
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40 error ("polyderiv: argument must be a vector"); |
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41 endif |
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42 |
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43 lp = length (p); |
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44 if (lp == 1) |
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45 q = 0; |
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46 return; |
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47 elseif (lp == 0) |
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48 q = []; |
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49 return; |
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50 end |
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51 |
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52 q = p (1:(lp-1)) .* [(lp-1):-1:1]; |
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53 |
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54 endfunction |
