ARCTAN2
ARCTAN2(Y,X) returns the angle that has a tangent equal to the Y/X. It differs from the ARCTAN function in that it will return an angle in the correct quadrant. The return value is from -Pi to Pi radians or -180 to 180 degrees. The units of the angle (degrees or radians) will depend on the unit choice made for trigonometric functions with the Unit System command.