How to get an angle between 2 Vectors?

Hey jblaswu ! Thanks for the quick response. Sorry about the post thing, I thought it would be more appropriate to post it here. Anyway…who is Xend and Xini ? this is for an AI controller…not the player. The AI doesn’t know where left and right is…I am giving it an angle and it just moves in that direction. The problem is that the angle is always positive.