gsp_estimate_lmax.m
2cb18aae5832master

gsp_estimate_lmax.m
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			function G = gsp_estimate_lmax(G)
			%GSP_ESTIMATE_LMAX estimates the maximum laplacian eigenvalue
			% Usage: G = gsp_estimate_lmax(G);
			%
			% Inputs parameters:
			% G : Graph structure (or cell array of graph structure)
			% Outputs parameters:
			% G : Graph structure (or cell array of graph structure)
			%
			% This function will compute an approximation of the maximum laplacian
			% eigenvalue and fill it in the field G.lmax*
			%
			% Runs Arnoldi algorithm with a large tolerance, then increases
			% calculated maximum eigenvalue by 1 percent. For much of the gspbox
			% machinery, we need to approximate the wavelet kernels on an
			% interval that contains the spectrum of L. The only cost of using
			% a larger interval is that the polynomial approximation over the
			% larger interval may be a slightly worse approxmation on the
			% actual spectrum. As this is a very mild effect, it is not likely
			% necessary to obtain very tight bonds on the spectrum of L
			%
			% This function is inspired by the sgwt_toolbox
			%
			% Url: http://lts2research.epfl.ch/gsp/doc/utils/gsp_estimate_lmax.php

			% Copyright (C) 2013-2016 Nathanael Perraudin, Johan Paratte, David I Shuman.
			% This file is part of GSPbox version 0.7.0
			%
			% This program 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.
			%
			% This program 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 this program. If not, see <http://www.gnu.org/licenses/>.

			% If you use this toolbox please kindly cite
			% N. Perraudin, J. Paratte, D. Shuman, V. Kalofolias, P. Vandergheynst,
			% and D. K. Hammond. GSPBOX: A toolbox for signal processing on graphs.
			% ArXiv e-prints, Aug. 2014.
			% http://arxiv.org/abs/1408.5781

			% Author: David K. Hammond, Nathanael Perraudin
			% Date: 15 March 2014


			if numel(G)>1
			Ng = numel(G);
			for ii = 1:Ng
			G{ii} = gsp_estimate_lmax(G{ii});
			end
			return;
			end


			try
			opts=struct('tol',5e-3,'p',min(G.N,10),'disp',0);
			lmax=eigs(G.L,1,'lm',opts);

			G.lmax=abs(lmax)*1.01; % just increase by 1 percent to be robust to error

			catch
			warning('GSP_ESTIMATE_LMAX: Cannot use the default method')
			G.lmax = 2*max(G.d);
			end

			if isfield(G,'Gm')
			G = gsp_estimate_oose_lmax(G);
			end

			end

iCAPs/packages/gspbox/utils/gsp_estimate_lmax.m2cb18aae5832master

gsp_estimate_lmax.mView Options

iCAPs/packages/gspbox/utils/gsp_estimate_lmax.m
2cb18aae5832master

gsp_estimate_lmax.m
View Options