function m=dualmean(varargin)% DUALMEAN Computes dual representation of mean vector.%% Synopsis:%  m = dualmean(num_data)%  m = dualmean(labels,y)%% Description:%  This function computes a vector m which allows to express the mean%  vector of data sample X [dim x num_data] in terms of dot products. %%  m = dualmean(num_data) computes a vector m [num_data x 1] such that %    mean(X,2) = X*m.%%  m = dualmean(labels,y) computes a vector m [length(y) x 1] such that%    mean(X(:,find(labels==y)),2) = X*m,%%  where labels [1 x num_data] is a vector of data labels and  y [1x1]  %  is a label od class which mean vector is to be computed.% % Example:%  Unlabeled data:%   data = load('riply_trn');%   ma = mean( data.X, 2)%   mb = data.X*dualmean(size(data.X,2))%%  Labeled data:%   data = load('riply_trn');%   ma1 = mean( data.X(:,find(data.y==1)),2)%   mb1 = data.X*dualmean(data.y,1)%   ma2 = mean( data.X(:,find(data.y==2)),2)%   mb2 = data.X*dualmean(data.y,2)%% See also %  DUALCOV.%% About: Statistical Pattern Recognition Toolbox% (C) 1999-2003, Written by Vojtech Franc and Vaclav Hlavac% <a href="http://www.cvut.cz">Czech Technical University Prague</a>% <a href="http://www.feld.cvut.cz">Faculty of Electrical Engineering</a>% <a href="http://cmp.felk.cvut.cz">Center for Machine Perception</a>% Modifications:% 16-may-2004, VF% 14-may-2004, VF% 22-Jan-2003, VF% 22-May-2001, V. Franc, createdif nargin == 2,  % labeled data  labels = varargin{1};  y = varargin{2};  num_data = length(labels);  m = zeros(num_data,1);  inx = find(labels==y);  m(inx) = ones(length(inx),1)/length(inx);else  % unlabeled data  num_data = varargin{1};  m = ones(num_data,1)/num_data;endreturn;% EOF