1. The problem statement, all variables and given/known data Hi I have a position given by the point a vector v points to. Now I have a function, which is only defined for the points on and inside a circle with radius 2 within this point. Can I write this interval as [tex] x,y \in [(x-v_x)^2-(y-v_y)^2=4] [/tex] ? Best, Niles.