在对Bayes++库的名称空间有了一个大概的了解之后，我们开始学习该名称空间下的第一个子类Bayesian_filter::Bayes_filter_base. 该类与其子类的继承关系图如下图所示。
Bayesian_filter::Bayes_filter_base对应的头文件和实现文件分别为bayesFlt.hpp和bayesFlt.cpp.
1. 接下来是第一个子类Bayesian_filter::Functional_filter,其对应的继承关系图如下：
2. Bayesian_filter::Information_state_filter
3. Bayesian_filter::Likelihood_filter
4. Bayesian_filter::Linrz_filter
5. Bayesian_filter::Sample_state_filter
6. Bayesian_filter::State_filter
