了解隐马尔科夫模型HMM的概念、组成和需要解决的问题；通过matlab分析和三个基本算法分析读研和就业问题：forward算法、Viterbi算法和Baum-Welch算法-Understand the concept of Hidden Markov Model HMM, composition and problems to be solved　matlab analysis by three basic algorithms: forward algorithm, Viterbi algorithm and Baum-Welch algorithm