why opencv NormalBayesClassifier.train() is run very very slowly which train data is small

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Hi, all i use opencv's NormalBayesClassifier.train() to train to train bayes model, the number of train data is 44518, and the num of class is 156, the num of attributes which in each vector is 156, and the matrix which is generated by the vectors is sparse, it has run about more than 5 hours, but has not train over, the program is still running at NormalBayesClassifier.train() function why?, Dose the opencv's NormalBayesClassifier.train() run slowly really?

thanks