常用公式latex记录
余弦相似度：
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cos(\theta) = {\sum_{i=1}^{n}{(x_i \times y_i)} \over {\sum_{i=1}^{n}{(x_i)^2} \times \sum_{i=1}^{n}{(y_i)^2}}}
cos(θ)=∑i=1n(xi)2×∑i=1n(yi)2∑i=1n(xi×yi)
cos(\theta) = {\sum_{i=1}^{n}{(x_i \times y_i)} \over {\sum_{i=1}{n}{(x_i)2} \times \sum_{i=1}{n}{(y_i)2}}}
均方误差：
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MSE(y,y^’) = {\sum_{i=1}^{n}{(y_i-y^’_i)^2} \over n}
MSE(y,y’)=n∑i=1n(yi−yi’)2
MSE(y,y^’) = {\sum_{i=1}{n}{(y_i-y’_i)^2} \over n}