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.
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Some math problems, e.g., complex number argument, require calculating the angle between the ray to the given point and positive semi-axis x. Many computer languages, e.g., javascript, have an atan2 (two-arguments arctangent) function to solve this task. Atan2 returns the angle in the range (-π, π] in contrast to ordinal arc tangent, which result is in -π/2 .. π/2.
atan2 is based on the arctangent function, but it expects two arguments to correctly determine the resulting quadrant.
atan2
Atan2 calculation algorithm
Arctan2 with all positive x is same as ordinal arc tangent:
, x>0
For other x values, arctan2 can be calculated according the following table:
| y<0 | y = 0 | y>0 | |
|---|---|---|---|
| x<0 | |||
| x=0 | undefined |
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