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## arc tan2 function

The `atan2` function is an inverse trigonometric function. The `atan2` function is a two-argument arc tangent (inverse of tan) function, which returns the arc tangent of a coordinate or point in two-dimensional space (n1, n2) calculated as atan(n2/n1).

Syntax:

    double atan2(n1,n2)

Semantics:

- n1, n2: The arguments n1 and n2 are expressions that resolve to numbers.
- return type: double.

  The resultant angle is expressed in radians and is in the range -pi through pi with the following exceptions:

  - Returns a NULL value in the following cases:
    - If either of the arguments resolves to a NULL value
    - If either of the arguments does not resolve to a number
  - Returns a NaN if either of the arguments resolves to NaN.

Example 12-75 arc tan2 function

    SELECT atan2(n1,n2) FROM Archery

Value of n1 | Value of n2 | Output
--- | --- | ---
1 | 1 | 0.7853981633974483
1 | sqrt(3) | 1.0471975511965976
2 | 0 | 1.5707963267948966