Categories:

Numeric Functions (Trigonometric)

# ATAN2¶

Computes the inverse tangent (arc tangent) of the ratio of its two arguments. For example, if x > 0, then the expression ATAN2(y, x) is equivalent to ATAN(y/x).

The arc tangent is the angle between:

• The X axis.

• The ray from the point (0,0) to the point (X, Y) (where X and Y are not both 0).

ATAN

## Syntax¶

ATAN2( <y> , <x> )


Note that the first parameter is the Y coordinate, not the X coordinate.

## Arguments¶

y

This parameter is the Y coordinate of the point at the end of the ray. The data type is DOUBLE.

x

This parameter is the X coordinate of the point at the end of the ray. The data type is DOUBLE.

## Returns¶

The data type of the returned value is DOUBLE.

The returned value is in radians, not degrees.

The returned value is a number in the interval [-pi, pi].

## Usage Notes¶

• If the data type of an argument is a numeric data type other than DOUBLE, then the value is converted to DOUBLE.

• If the data type of an argument is string, the value is converted to DOUBLE if possible.

• If the data type of an argument is any other data type, the function returns an error.

• If either argument is NULL, the returned value is NULL.

## Examples¶

SELECT ATAN2(5, 5);

--------------+
ATAN2(5, 5)  |
--------------+
0.7853981634 |
--------------+