简单分析一下，详情如图所示
设F(x,y,z)=z+e^z-xy 则Fx=-y,Fy=-x,Fz=1+e^z αz/αx=-Fx/Fz=y/(1+e^z),αz/αy=-Fy/Fz=x/(1+e^z) σ2z/σxσy=α(αz/αx)/αy=-y/(1+e^z)^2*(αz/αy)=-xy/(1+e^z)^3
