** Next:** Second-order methods
** Up:** Classical Linear Transformations
** Previous:** Classical Linear Transformations

Several principles have been developed in statistics, neural computing,
and signal processing to find a
suitable linear representation of a random variable.
In this Section, we discuss classical methods for determining the
linear transformation as in (2).
All the methods discussed in this paper are based on using centered
variables. In other words, the mean of the random vector is subtracted.
To simplify the discussion, it is henceforth assumed that the variable
is centered, which means that it has already been transformed by
,
where
is the original non-centered
variable.

*Aapo Hyvarinen*

*1999-04-23*