基于最小错误率的贝叶斯决策 （1）要决策分类的类别数是一定的；（2）每一类出现的“先验概率”已知；（3）每一类的“类条件概率密度”已知；(Bayesian Decision Based on Minimum Error Rate(1) the "prior probabilities" of each class are known; (2) the "conditional probability density" of each class is known;)