# 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
```