Divergence (発散)

A=Axx+Ayy+Azz=1ρ(ρAρ)ρ+1ρAϕϕ+Azz=1r2(r2Ar)r+1rsinθθ(Aθsinθ)+1rsinθAϕϕ\begin{aligned} \nabla \cdot \mathbf{A} & = {\partial A_x \over \partial x} + {\partial A_y \over \partial y} + {\partial A_z \over \partial z} \\ & = {1 \over \rho}{\partial \left( \rho A_\rho \right) \over \partial \rho} + {1 \over \rho}{\partial A_\phi \over \partial \phi} + {\partial A_z \over \partial z} \\ & = {1 \over r^2}{\partial \left( r^2 A_r \right) \over \partial r} + {1 \over r\sin\theta}{\partial \over \partial \theta} \left( A_\theta\sin\theta \right) + {1 \over r\sin\theta}{\partial A_\phi \over \partial \phi} \end{aligned}