You have to define first the angle relative to what.
Let's say you want the angle relative to x-y plane. A vector that is perpendicular to x-y plane is [0 0 1] then you can compute the angle of your vector to that plane as:
V1=[u,v,w];
V2=[0,0,1];
Angle_Rad=pi/2-acos(dot(V1,V2)./(norm(V1).*norm(V2)))
Angle_Deg=Angle_Rad*180/pi
