ATAN

Returns the inverse tangent value of a numeric expression

Syntax

ATAN( expr )

Arguments

Parameter	Description
`expr`	Numeric expression

Returns

Always returns a floating point result of the inverse tangent, in radians.

Notes

The result is given in radians, in the range [-π/2, π/2].
If the input value is NULL, the result is NULL.

Examples

For these examples, consider the following table and contents:

CREATE TABLE trig(f DOUBLE);

INSERT INTO trig VALUES (-9999), (-3), (-2), (-1.732)
, (-1), (-0.5), (0), (0.5)
, (1), (1.732), (2), (3), (9999);

Inverse tangent of 1 (= π/4)

numbers=> SELECT ATAN(1);
atan
----
0.7853981633974483

Computing inverse tangent for a column

numbers=> SELECT f, ASIN(f) FROM trig;
f      | atan
-------+------------
 -9999 | -1.57069632
    -3 | -1.24904577
    -2 | -1.10714872
-1.732 | -1.04718485
    -1 | -0.78539816
  -0.5 | -0.46364761
     0 |         0.0
   0.5 |  0.46364761
     1 |  0.78539816
 1.732 |  1.04718485
     2 |  1.10714872
     3 |  1.24904577
  9999 |  1.57069632