PostgreSQL ATAN2() Function

The PostgreSQL ATAN2() function returns arc tangent of two numbers. This function uses sign of both numbers to determine the quadrant for the result. The other variant of this function is ATAN2D() which returns the result in degrees.

Syntax

/* returns result in radians */
ATAN2(y, x)

/* returns result in degrees */
ATAN2D(y, x)

Parameters

Return Value

Returns the arc tangent of two numbers.

Example 1:

The example below shows the usage of ATAN2() function.

SELECT ATAN2(PI(), 2);
Result: 1.0038848218538872

SELECT ATAN2(3, 5);
Result: 0.5404195002705842

SELECT ATAN2(2, 2);
Result: 0.7853981633974483

SELECT ATAN2(2, -2);
Result: 2.356194490192345

SELECT ATAN2(-2, 2);
Result: -0.7853981633974483

SELECT ATAN2(-2, -2);
Result: -2.356194490192345

SELECT ATAN2D(2, 2);
Result: 45

SELECT ATAN2D(2, -2);
Result: 135

SELECT ATAN2D(-2, 2);
Result: -45

SELECT ATAN2D(-2, -2);
Result: -135

Example 2:

Consider a database table called Sample with the following records:

To calculate the arc tangent of records of column y and column x, the following query can be used:

SELECT *, ATAN2(y, x) AS ATAN2_Value FROM Sample;

This will produce the result as shown below: