Returns the angle (in radians) of the specified tangent.
atan(tangent )
is the tangent of the angle, expressed as a column name, variable, or constant of type float, real, double precision, or any datatype that can be implicitly converted to one of these types.
select atan(0.50)
-------------------- 0.463648
atan, a mathematical function, returns the angle (in radians) of a tangent with the specified value.
ANSI SQL – Compliance level: Transact-SQL extension.
Any user can execute atan.