Returns the arctangent of the x and y coordinates specified by expression1 and expression2.

Syntax

ATAN2 ( expression1 , expression2 )

Notes

  • ATAN2 takes the ratio of two sides of a right triangle and returns the corresponding angle. The ratio is the length of the side opposite the angle divided by the length of the side adjacent to the angle.
  • expression1 and expression2 specify the x and y coordinates of the end of the hypotenuse opposite the angle.
  • The result is expressed in radians and is in the range -pi/2 to pi/2 radians. To convert degrees to radians, multiply degrees by pi/180. To convert radians to degrees, multiply radians by 180/pi.
  • Both expression1 and expression2 must evaluate to approximate numeric data types.

Example

The following example illustrates two ways to use the ATAN2 function:

select atan2 (1,1) * (180/ pi()) 'Arctangent in degrees' from syscalctable;
 ARCTANGENT IN DEGREES
----------------------- 
45.000000000000000
 1 record selected
  select atan2 (1,1) 'Arctangent in radians' from syscalctable;
 ARCTANGENT IN RADIANS
----------------------- 
0.785398163397448
 1 record selected

Compatibility

ODBC compatible