An abstract class to calculate forward and backward probabiliies. This class should not be instantiated directly, but should be used through a derived class which implements proper scaling of variables. This class is just meant to encapsulate the basic foward and backward algorithms, and allow derived classes to deal with the problems of multiplying probabilities. Derived class of this must implement: o _forward_recursion -- Calculate the forward values in the recursion using some kind of technique for preventing underflow errors. o _backward_recursion -- Calculate the backward values in the recursion step using some technique to prevent underflow errors.
Public Member Functions
Private Member Functions