Mercurial > forge
comparison main/special-matrix/wilkinson.m @ 0:6b33357c7561 octave-forge
Initial revision
| author | pkienzle |
|---|---|
| date | Wed, 10 Oct 2001 19:54:49 +0000 |
| parents | |
| children | 2ac2777b30bc |
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| -1:000000000000 | 0:6b33357c7561 |
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| 1 ## Copyright (C) 1999 Peter Ekberg | |
| 2 ## | |
| 3 ## This program is free software; you can redistribute it and/or modify it | |
| 4 ## under the terms of the GNU General Public License as published by | |
| 5 ## the Free Software Foundation; either version 2, or (at your option) | |
| 6 ## any later version. | |
| 7 ## | |
| 8 ## This program is distributed in the hope that it will be useful, but | |
| 9 ## WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 10 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| 11 ## General Public License for more details. | |
| 12 ## | |
| 13 ## You should have received a copy of the GNU General Public License | |
| 14 ## along with this program; see the file COPYING. If not, write to the Free | |
| 15 ## Software Foundation, 59 Temple Place - Suite 330, Boston, MA | |
| 16 ## 02111-1307, USA. | |
| 17 | |
| 18 ## usage: wilkinson (n) | |
| 19 ## | |
| 20 ## Return the Wilkinson matrix of order n. | |
| 21 ## | |
| 22 ## See also: hankel, vander, sylvester_matrix, hilb, invhilb, toeplitz | |
| 23 ## hadamard, rosser, compan, pascal | |
| 24 | |
| 25 ## Author: peda | |
| 26 | |
| 27 function retval = wilkinson (n) | |
| 28 | |
| 29 if (nargin != 1) | |
| 30 usage ("wilkinson (n)"); | |
| 31 endif | |
| 32 | |
| 33 nmax = length (n); | |
| 34 if ~(nmax == 1) | |
| 35 error ("wilkinson: expecting scalar argument, found something else"); | |
| 36 endif | |
| 37 | |
| 38 side = ones(n-1,1); | |
| 39 center = abs(-(n-1)/2:(n-1)/2); | |
| 40 retval = diag(side, -1) + diag(center) + diag(side, 1); | |
| 41 | |
| 42 endfunction |