[err,SphereSc,Radius] = overlapping_sphere_fmins(X,TrueSc,Loc,Orient,Weight,Vertices);

OVERLAPPING_SPHERE_FMINS - for use with OVERLAPPING_SPHERE function [err,SphereSc,Radius] = overlapping_sphere_fmins(X,TrueSc,Loc,Orient,Weight,Vertices); calculate the error between true and estimated weighting scalars

- colnorm C:\BrainStorm_2001\Toolbox\colnorm.m
- weighting_scalar C:\BrainStorm_2001\Toolbox\weighting_scalar.m

- overlapping_sphere C:\BrainStorm_2001\Toolbox\overlapping_sphere.m

function [err,SphereSc,Radius] = overlapping_sphere_fmins(X,TrueSc,Loc,Orient,Weight,Vertices); %OVERLAPPING_SPHERE_FMINS - for use with OVERLAPPING_SPHERE % function [err,SphereSc,Radius] = overlapping_sphere_fmins(X,TrueSc,Loc,Orient,Weight,Vertices); % calculate the error between true and estimated weighting scalars %<autobegin> ---------------------- 26-May-2004 11:34:04 ----------------------- % --------- Automatically Generated Comments Block Using AUTO_COMMENTS --------- % % CATEGORY: Forward Modeling % % Alphabetical list of external functions (non-Matlab): % toolbox\colnorm.m % toolbox\weighting_scalar.m % % At Check-in: $Author: Mosher $ $Revision: 12 $ $Date: 5/26/04 10:02a $ % % This software is part of BrainStorm Toolbox Version 2.0 (Alpha) 24-May-2004 % % Principal Investigators and Developers: % ** Richard M. Leahy, PhD, Signal & Image Processing Institute, % University of Southern California, Los Angeles, CA % ** John C. Mosher, PhD, Biophysics Group, % Los Alamos National Laboratory, Los Alamos, NM % ** Sylvain Baillet, PhD, Cognitive Neuroscience & Brain Imaging Laboratory, % CNRS, Hopital de la Salpetriere, Paris, France % % See BrainStorm website at http://neuroimage.usc.edu for further information. % % Copyright (c) 2004 BrainStorm by the University of Southern California % This software distributed under the terms of the GNU General Public License % as published by the Free Software Foundation. Further details on the GPL % license can be found at http://www.gnu.org/copyleft/gpl.html . % % FOR RESEARCH PURPOSES ONLY. THE SOFTWARE IS PROVIDED "AS IS," AND THE % UNIVERSITY OF SOUTHERN CALIFORNIA AND ITS COLLABORATORS DO NOT MAKE ANY % WARRANTY, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO WARRANTIES OF % MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, NOR DO THEY ASSUME ANY % LIABILITY OR RESPONSIBILITY FOR THE USE OF THIS SOFTWARE. %<autoend> ------------------------ 26-May-2004 11:34:04 ----------------------- % John C. Mosher, Ph.D. See Copyright.m file for information % % $Date: 5/26/04 10:02a $ $Revision: 12 $ Center = X(1:3); Radius = X(4); N = size(Vertices,2); % number of vertices OneN = ones(1,N); % convenient vector of ones % two cases here. 'Scalar' attempts to fit the weighting scalar function between % the true surface and the spherical surface. The problem is a strong dependency % on surface normals that appears to skew the spheres. Theoretical assumption flaw % may be that the fictitious currents are not that similar. % 'Weights' instead simply fits a sphere to the vertices, but uses the Scalar function % to weight the least-squares fit. % Need to test more formally % leave one uncommented: %switch 'Scalar' switch 'Weights' case 'Scalar' % First synthesize the normals as vectors passing from the center through the vertices [ignore,Normals] = colnorm(Vertices - Center(:,OneN)); % then synthesize vertices as points on the sphere Vertices = Radius * Normals + Center(:,OneN); % now calculate the weighting scalar to the sphere points SphereSc = weighting_scalar(Loc,Orient,Weight,Vertices,Normals); % now calculate the least-squares error between the two scalar sets err = sum((TrueSc - SphereSc).^2); case 'Weights' % Scale the true scalar to be a weighting function Weights = abs(TrueSc)/sum(abs(TrueSc)); % don't care about sign. % extracted from sphererr.m b = Vertices - Center(:,OneN); % data - estimated center % form distances to center estimate b = sqrt(sum(b.^2))'; % col vector of distances r = sum(b.*Weights); % average distance weighted by Scalar % squared error, weighted by scalars err = ((b-r).*Weights).^2; % squared error between distances and sphere % map for informative purposes SphereSc = err; err = sum(err); % sum squared error Radius = r; % overrides what the user sent end return

Produced by color_mat2html, a customized BrainStorm 2.0 (Alpha) version of mat2html on Tue Oct 12 12:05:14 2004

Cross-Directory links are: ON