用c实现hmm,给定观察值序列和HMM模型，利用前向后向算法求取其概率-Using c to achieve hmm, for a given sequence of observations and the HMM model, using forward and backward algorithm to compute the probability

功能：根据给定的观察序列，用BaumWelch算法估计HMM模型参数-Features: according to the given observation sequence estimation algorithm with BaumWelch HMM model parameters