class TMVA::VariableTransformBase: public TObject

 destructor

 reset the trees branch addresses and have them point to the event

 the fEvent is used to hold the event after the
 transformation. It should not hold any connections to the
 outside world, all its Variables shold be stored locally, and
 the external link pointers should be 0 [creating the event from
 the fVariables list, does not always guarantie that, so it has
 to be explicitely ensured]

 in addition all variables need to be float

 read event from a tree into memory
 after the reading the event transformation is called

 update min and max of a given variable and a given transformation method

 method to calculate minimum, maximum, mean, and RMS for all
 variables used in the MVA

 create histograms from the input variables
 - histograms for all input variables
 - scatter plots for all pairs of input variables

 prints ranking of input variables

 write the list of variables (name, min, max) for a given data
 transformation method to the stream

 Read the variables (name, min, max) for a given data
 transformation method from the stream. In the stream we only
 expect the limits which will be set

 accessors

 provides string vector describing explicit transformation

 variable ranking

 writer of function code