### 5.54.4 Divergence : divergence

divergence takes two arguments : a vector field of dimension n depending on n real variables.
divergence returns the divergence of F that is the sum of the derivative of the k-th component with respect to the k-th variable. For example in dimension n=3:

divergence([A,B,C],[x,y,z])=∂ A/∂ x+∂ B/∂ y+∂ C/∂ z

Input :

divergence([x*z,-y`^`2,2*x`^`y],[x,y,z])

Output :

z+-2*y