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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 ## usage: vander (c) |
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21 ## |
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22 ## Return the Vandermonde matrix whose next to last column is c. |
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23 ## |
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24 ## See also: hankel, sylvester_matrix, hilb, invhilb, toeplitz |
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25 |
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26 ## Author: jwe |
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27 |
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28 function retval = vander (c) |
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29 |
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30 if (nargin != 1) |
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31 usage ("vander (c)"); |
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32 endif |
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33 |
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34 nr = rows (c); |
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35 nc = columns (c); |
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36 if (nr == 1 && nc == 1) |
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37 retval = 1; |
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38 elseif (nr == 1 || nc == 1) |
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39 n = length (c); |
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40 if (n > 0) |
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41 retval = zeros (n, n); |
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42 for i = 1:n |
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43 tmp = c(i); |
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44 for j = 1:n |
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45 retval (i, j) = tmp ^ (n - j); |
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46 endfor |
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47 endfor |
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48 endif |
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49 else |
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50 error ("vander: argument must be a vector"); |
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51 endif |
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52 |
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53 endfunction |
