Teorema di Gauss

Forma vettoriale:

$$\int_S \vec{\phi}\ \vec{n}\ dS=\int_V\nabla\vec{\phi}\ dv$$ (B.2)

Forma scalare:

$$\left. \int_S \phi_i\ n_i\ dS= \int_V \ensuremath{\frac{\partial \phi_i}{\partial x_i}}dv \right\vert _{(i=1,2,3)}$$ (B.3)