### TMVA

TMVA version 4.1.2 is included in this root release. The changes with respect to ROOT 5.28 / TMVA 4.1.0 are in detail:

#### Variable transformations

- Variable transformations can now be applied to a user-defined subset of variables (and regression targets).
- Enable variable transformations for general boosting
- Extended PDEFoam functionality:
  - Multiclass classification by training of one discriminator foam for each variable.
  - The cell tree can now be plotted from the macro test/PlotFoams. This makes it easyer to compare the PDEFoam structure to a decision tree.
  - Variable importance ranking by counting the number of cuts made in each dimension. The variable, for which the most cuts were done is ranked highest.
- Fixed the size of the sampling box in PDEFoam: In TMVA 4.1.0 the size of the PDEFoam sampling box in each dimension was 2*VolFrac times the foam size. This was contrary to the intention and the documentation in the UserGuide and is now corrected: In TMVA 4.1.1 the size of the PDEFoam sampling box in each dimension is now VolFrac times the foam size. This implies that in TMVA 4.1.1 the VolFrac value for training a PDEFoam must be doubled in order to give the same results as in TMVA 4.1.0. The default VolFrac value was also changed from 0.0333 to 0.0666.
- New configuration variable "NbinsMVAoutput" defining the bins of the MVA output variables in the TMVA training plots produced via the GUI. As always, Config settings can be modified in the training script via, eg, the command (TMVA::gConfig().GetVariablePlotting()).fNbinsMVAoutput = 50; to be called AFTER initialising the TMVA Factory object.

#### Bug fixes

- Requested number of training and testing events was not correct when pre-selection cuts were applied. Now the number of requested events scales with the preselection efficiency and hence does not need to be adjusted with the pre-selection. This also corrects the problems seen in the Category classifierm, where pre-selection is used to build the categories.
- Correct histogram boundaries in PlotVariable.
- Correct scanning procedure in OptimizeTuningParameters.
- Print the significance formula that is actually used
- Small speed improvement for PDEFoam functions.
- Fix for MethodBoost which ensures that the method options for the boosted classifier are handled correctly during boosting.
- Fixed problems in classification of some methods when booking background training tree before signal one.
- Fixed preprocessing transformation bug in HMatrix
- Several minor bug fixes for version 4.1.2