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1 ## Copyright (C) 1999 Peter Ekberg |
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2 ## |
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3 ## This program is free software; you can redistribute it and/or modify it |
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4 ## under the terms of the GNU General Public License as published by |
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5 ## the Free Software Foundation; either version 2, or (at your option) |
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6 ## any later version. |
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7 ## |
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8 ## This program is distributed in the hope that it will be useful, but |
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9 ## WITHOUT ANY WARRANTY; without even the implied warranty of |
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10 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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11 ## General Public License for more details. |
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12 ## |
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13 ## You should have received a copy of the GNU General Public License |
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14 ## along with this program; see the file COPYING. If not, write to the Free |
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15 ## Software Foundation, 59 Temple Place - Suite 330, Boston, MA |
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16 ## 02111-1307, USA. |
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17 |
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18 ## usage: wilkinson (n) |
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19 ## |
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20 ## Return the Wilkinson matrix of order n. |
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21 ## |
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22 ## See also: hankel, vander, sylvester_matrix, hilb, invhilb, toeplitz |
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23 ## hadamard, rosser, compan, pascal |
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24 |
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25 ## Author: peda |
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26 |
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27 function retval = wilkinson (n) |
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28 |
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29 if (nargin != 1) |
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30 usage ("wilkinson (n)"); |
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31 endif |
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32 |
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33 nmax = length (n); |
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34 if ~(nmax == 1) |
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35 error ("wilkinson: expecting scalar argument, found something else"); |
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36 endif |
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37 |
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38 side = ones(n-1,1); |
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39 center = abs(-(n-1)/2:(n-1)/2); |
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40 retval = diag(side, -1) + diag(center) + diag(side, 1); |
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41 |
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42 endfunction |
