atan method

Composes a function that returns the arctangent of this function's field result across its extent.

The function result is the principal value, in radians, of the inverse tangent of the function's field result, so the function result will lie between -pi/2 and pi/2.

The function result has no data where this function's field result has no data.

The function result extent equals that of this function's field result.

Return Value: A function that returns the arctangent of this function's field result across its extent.