ATN2¶
Returns the inverse tangent of the ratio of x and y.
ATN2(y,x) = ATAN(y/x)
This represents the angle in radians from the positive x-axis of a plane and the point (x, y) on it, with positive sign for the upper half-plane.
Syntax¶
ATN2( expr1, expr2 )
Arguments¶
Parameter |
Description |
|---|---|
|
Numeric expression representing the |
|
Numeric expression representing the |
Returns¶
When using the ATN2 floating point number scalar function, real arguments are automatically cast to double precision.
Notes¶
The result is given in radians, in the range
(-π, π].If the input value is NULL, the result is NULL.
Examples¶
Inverse tangent of (1, 0) (= π/2)¶
numbers=> SELECT ATN2(1,0);
atn2
----
1.5707963267948966
Inverse tangent of x=0.5, y=SQRT(3)/2 (= π/3, or 60°)¶
Use SQRT to simplify input and DEGREES to convert the result from radians.
numbers=> SELECT ATN2(0.5*SQRT(3), 0.5), DEGREES(ATN2(0.5*SQRT(3), 0.5));
atn2 | degrees
-------+--------
1.0472 | 60