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1 # Copyright (C) 1995 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 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, 675 Mass Ave, Cambridge, MA 02139, USA. |
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18 |
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19 function p = polyderiv (p) |
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20 |
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21 # usage: polyderiv (p) |
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22 # |
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23 # Returns the coefficients of the derivative of the polynomial whose |
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24 # coefficients are given by vector p. |
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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 # Written by Tony Richardson (amr@mpl.ucsd.edu) June 1994. |
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30 |
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31 if (nargin != 1) |
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32 usage ("polyderiv (vector)"); |
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33 endif |
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34 |
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35 if (is_matrix (p)) |
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36 error ("argument must be a vector"); |
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37 endif |
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38 |
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39 lp = length (p); |
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40 if (lp == 1) |
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41 p = 0; |
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42 return; |
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43 elseif (lp == 0) |
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44 p = []; |
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45 return; |
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46 end |
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47 |
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48 p = p (1:(lp-1)) .* [(lp-1):-1:1]; |
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49 |
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50 endfunction |
