List of abbreviations

DCT	Discrete cosine transform
EM	Expectation maximisation
FA	Factor analysis
HNFA	Hierarchical nonlinear factor analysis
HNFA+VM	Hierarchical nonlinear factor analysis with variance modelling
ICA	Independent component analysis
KL	Kullback-Leibler (divergence)
MAP	Maximum a posteriori (solution)
ML	Maximum likelihood (solution)
MLP	Multi-layer perceptron (network)
NCA	Nonlinear component analysis
NFA	Nonlinear factor analysis
PCA	Principal component analysis
pdf	Probability density function
RBF	Radial basis function
SOM	Self-organising map
std	Standard deviation