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annotate scripts/polynomial/polyvalm.m @ 1267:69501f98669d

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[project @ 1995-04-20 19:10:05 by jwe] Initial revision
author jwe
date Thu, 20 Apr 1995 19:10:05 +0000
parents f558749713f1
children 611d403c7f3d
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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 y = polyvalm (c, x)
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20
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21 # usage: polyvalm (c, x)
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22 #
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23 # Evaluate a polynomial in the matrix sense.
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24 #
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25 # In octave, a polynomial is represented by it's coefficients (arranged
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26 # in descending order). For example a vector c of length n+1 corresponds
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27 # to the following nth order polynomial
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28 #
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29 # p(x) = c(1) x^n + ... + c(n) x + c(n+1).
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30 #
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31 # polyvalm(c,X) will evaluate the polynomial in the matrix sense, i.e. matrix
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32 # multiplication is used instead of element by element multiplication as is
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33 # used in polyval.
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34 #
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35 # X must be a square matrix.
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36 #
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37 # SEE ALSO: polyval, poly, roots, conv, deconv, residue, filter,
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38 # polyderiv, polyinteg
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39
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40 # Written by Tony Richardson (amr@mpl.ucsd.edu) June 1994.
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41
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42 if(nargin != 2)
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43 usage ("polyvalm (c, x)");
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44 endif
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45
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46 if (is_matrix (c))
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47 error("poly: first argument must be a vector.");
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48 endif
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49
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50 if(! is_square (x))
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51 error("poly: second argument must be a square matrix.");
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52 endif
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53
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54 [v, d] = eig(x);
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56 y = v * diag (polyval (c, diag (d))) * v';
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57
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58 endfunction