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comparison scripts/sparse/normest.m @ 6222:07d967f75dba

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[project @ 2007-01-03 20:15:15 by jwe]
author jwe
date Wed, 03 Jan 2007 20:15:16 +0000
parents 0a259ae4375e
children 2c85044aa63f
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6221:8e0f1eda266b 6222:07d967f75dba
1 ## Copyright (C) 2006 David Bateman 1 ## Copyright (C) 2006 David Bateman and Marco Caliari
2 ## Copyright (C) 2006 Marco Caliari
3 ## 2 ##
4 ## This program is free software; you can redistribute it and/or modify 3 ## This program is free software; you can redistribute it and/or modify
5 ## it under the terms of the GNU General Public License as published by 4 ## it under the terms of the GNU General Public License as published by
6 ## the Free Software Foundation; either version 2 of the License, or 5 ## the Free Software Foundation; either version 2 of the License, or
7 ## (at your option) any later version. 6 ## (at your option) any later version.
16 ## Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 15 ## Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
17 ## 02110-1301 USA 16 ## 02110-1301 USA
18 17
19 ## -*- texinfo -*- 18 ## -*- texinfo -*-
20 ## @deftypefn {Function File} {[@var{n}, @var{c}] =} normest (@var{a}, @var{tol}) 19 ## @deftypefn {Function File} {[@var{n}, @var{c}] =} normest (@var{a}, @var{tol})
21 ## 20 ## Estimate the 2-norm of the matrix @var{a} using a power series
22 ## Estimates the 2-norm of the matrix @var{a} using a power series
23 ## analysis. This is typically used for large matrices, where the cost 21 ## analysis. This is typically used for large matrices, where the cost
24 ## of calculating the @code{norm{@var{a})} is prohibitive and an approximation 22 ## of calculating the @code{norm (@var{a})} is prohibitive and an approximation
25 ## to the 2-norm is acceptable. 23 ## to the 2-norm is acceptable.
26 ## 24 ##
27 ## @var{tol} is the tolerance to which the 2-norm is calculated. By default 25 ## @var{tol} is the tolerance to which the 2-norm is calculated. By default
28 ## @var{tol} is 1e-6. @var{c} returns the number of iterations needed for 26 ## @var{tol} is 1e-6. @var{c} returns the number of iterations needed for
29 ## @code{normest} to converge. 27 ## @code{normest} to converge.