Mercurial > octave-libgccjit
view scripts/special-matrix/wilkinson.m @ 8964:f4f4d65faaa0
Implement sparse * diagonal and diagonal * sparse operations, double-prec only.
Date: Sun, 8 Mar 2009 16:28:18 -0400
These preserve sparsity, so eye(5) * sprand (5, 5, .2) is *sparse*
and not dense. This may affect people who use multiplication by
eye() rather than full().
The liboctave routines do *not* check if arguments are scalars in
disguise. There is a type problem with checking at that level. I
suspect we want diag * "sparse scalar" to stay diagonal, but we have
to return a sparse matrix at the liboctave. Rather than worrying
about that in liboctave, we cope with it when binding to Octave and
return the correct higher-level type.
The implementation is in Sparse-diag-op-defs.h rather than
Sparse-op-defs.h to limit recompilation. And the implementations
are templates rather than macros to produce better compiler errors
and debugging information.
author | Jason Riedy <jason@acm.org> |
---|---|
date | Mon, 09 Mar 2009 17:49:13 -0400 |
parents | a1dbe9d80eee |
children | 3140cb7a05a1 |
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## Copyright (C) 1999, 2006, 2007 Peter Ekberg ## ## 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 3 of the License, 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, see ## <http://www.gnu.org/licenses/>. ## -*- texinfo -*- ## @deftypefn {Function File} {} wilkinson (@var{n}) ## ## Return the Wilkinson matrix of order @var{n}. ## ## @seealso{hankel, vander, sylvester_matrix, hilb, invhilb, toeplitz ## hadamard, rosser, compan, pascal} ## @end deftypefn ## Author: Peter Ekberg ## (peda) function retval = wilkinson (n) if (nargin != 1) print_usage (); endif nmax = length (n); if (! (nmax == 1)) error ("wilkinson: expecting scalar argument, found something else"); endif side = ones (n-1, 1); center = abs (-(n-1)/2:(n-1)/2); retval = diag (side, -1) + diag (center) + diag (side, 1); endfunction