# ATAN

Elemental Intrinsic Function (Generic): Produces the arctangent of an argument.

result = ATAN (x)

result = ATAN (y,x)

y | (Input) Must be of type real.
x | (Input) If y appears, x must be of type real with the same kind type parameter as y. If y has the value zero, x must not have the value zero. If y does not appear, x must be of type real or complex.

## Results

The result type and kind are the same as x.

If y appears, the result is the same as the result of ATAN2 (y, x).

If y does not appear, the real part of the result is expressed in radians and lies in the range -pi/2 <= ATAN (x) <= pi/2.

Specific Name | Argument Type | Result Type
--- | --- | ---
ATAN | REAL(4) | REAL(4)
DATAN | REAL(8) | REAL(8)
QATAN | REAL(16) | REAL(16)

## Example

ATAN (1.5874993) has the value 1.008666.

ATAN (2.679676, 1.0) has the value 1.213623.

Parent topic: A to B