Mercurial > octave-nkf
view scripts/special-matrix/invhilb.m @ 1315:611d403c7f3d
[project @ 1995-06-25 19:56:32 by jwe]
author | jwe |
---|---|
date | Sun, 25 Jun 1995 19:56:32 +0000 |
parents | 3f257ab07921 |
children | 5d29638dd524 |
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# Copyright (C) 1993, 1994, 1995 John W. Eaton # # This file is part of Octave. # # Octave is free software; you can redistribute it and/or modify it # under the terms of the GNU General Public License as published by the # Free Software Foundation; either version 2, or (at your option) any # later version. # # Octave is distributed in the hope that it will be useful, but WITHOUT # ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or # FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License # for more details. # # You should have received a copy of the GNU General Public License # along with Octave; see the file COPYING. If not, write to the Free # Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. function retval = invhilb (n) # usage: invhilb (n) # # Return the inverse of a Hilbert matrix of order n. This is slow but # exact. Compare with inv (hilb (n)). # # See also: hankel, vander, hadamard, hilb, toeplitz if (nargin != 1) usage ("invhilb (n)"); endif nmax = length (n); if (nmax == 1) retval = zeros (n); for l = 1:n for k = l:n tmp = 1; for i = 1:n tmp = tmp * (i + k - 1); endfor for i = 1:n if (i != k) tmp = tmp * (l + i - 1); endif endfor for i = 1:n if (i != l) tmp = tmp / (i - l); endif endfor for i = 1:n if (i != k) tmp = tmp / (i - k); endif endfor retval (k, l) = tmp; retval (l, k) = tmp; endfor endfor else error ("hilb: expecting scalar argument, found something else"); endif endfunction