1. 一般的写法
$$
P(Y=c_k|X=x)=\frac{P(Y=c_k)\prod_{j}P(X^{(j)}=x^{(j)}|Y=c_k)}{\sum_{k}P(Y=c_k)\prod_{j}P(X^{(j)}=x^{(j)}|Y=c_k)}
$$
效果展示为：
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P(Y=c_k|X=x)=\frac{P(Y=c_k)\prod_{j}P(X^{(j)}=x^{(j)}|Y=c_k)}{\sum_{k}P(Y=c_k)\prod_{j}P(X^{(j)}=x^{(j)}|Y=c_k)}
P(Y=ck∣X=x)=∑kP(Y=ck)∏jP(X(j)=x(j)∣Y=ck)P(Y=ck)∏jP(X(j)=x(j)∣Y=ck)
我们可以看到，
∏
\prod
∏的下标的位置不在正下方。
2. 解决方法，加\limits_{}
代码为：
$$
P(Y=c_k|X=x)=\frac{P(Y=c_k)\prod \limits_{j}P(X^{(j)}=x^{(j)}|Y=c_k)}{\sum \limits_{k}P(Y=c_k)\prod \limits_{j}P(X^{(j)}=x^{(j)}|Y=c_k)}
$$
效果展示为：
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P(Y=c_k|X=x)=\frac{P(Y=c_k)\prod \limits_{j}P(X^{(j)}=x^{(j)}|Y=c_k)}{\sum \limits_{k}P(Y=c_k)\prod \limits_{j}P(X^{(j)}=x^{(j)}|Y=c_k)}
P(Y=ck∣X=x)=k∑P(Y=ck)j∏P(X(j)=x(j)∣Y=ck)P(Y=ck)j∏P(X(j)=x(j)∣Y=ck)
