e^z=xyz两边对x求偏导e^z*z'(x)=y(z+x*z'(x))z'(x)=yz/(e^z-xy)∂z/∂x=yz/(e^z-xy)原式对y求偏导e^z*z'(y)=x(z+y*z'(y))∂z/∂y=xz/(e^z-xy)dz=∂z/∂x*dx+∂z/∂y*dy=yz/(e^z-xy)*dx+xz/(e^z-xy)*dy
