| 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
Czech Technical University Prague
Faculty of Electrical Engineering
Center for Machine Perception
Modifications:
16-may-2004, VF
14-may-2004, VF
22-Jan-2003, VF
22-May-2001, V. Franc, created