Compute the directional derivative of the function

$f(x,y,z)=xarctan(\frac{y+2z}{z})$

at the point $(x,y,z)=(2,-3,1)$ in the direction of the vector vec$(v)=($:$2,-1,1$:$).$

$D_{\text{v}\text{e}\text{c}(v)}f(2,-3,1)=$

Give the value with two decimal places.