Equation Icon  ( ) ∂ ∂ ∂t-− ∂x- (At − Ax) = 0, ( ) -∂- ∂-- -∂- ∂t − ∂x Ay = ∂y (At − Ax ), ( ) -∂-− ∂-- Az = -∂-(At − Ax ), ∂t ∂x ∂z