举例：二元高斯分布的密度函数(\(X\),\(Y\)不独立)\(f_{X,Y}\left(x,y\right)=\frac{1}{2\pi\sigma_{x}\sigma_{y}\sqrt{1-\rho^2}}\exp\left(-\frac{1}{2(1-\rho)^2}\left[\frac{(x-\mu_{x})^2}{\sigma_{x}^2}-2\rho\frac{(x-\mu_{x})(t-\mu_{y})}{\sigma_{x}\si