Two arguments arctangent
The calculator gives an angle between positive axis x and the ray to the given point from point 0. The result corresponds to atan2 function, implemented in many computer languages and math libraries.
atan2 is based on the arctangent function, but it expects two arguments to correctly determine the resulting quadrant.
Atan2 calculation algorithm
Arctan2 with all positive x is same as ordinal arc tangent:
For other x values, arctan2 can be calculated according the following table:
|y<0||y = 0||y>0|