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).
See also:

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 must be FLOAT.

x

This parameter is the X coordinate of the point at the end of the ray. The data type must be FLOAT.

Returns

This function returns a value of type FLOAT.

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 |
+--------------+