Returns a number specifying the arctangent of the given number parameter. In other words, it returns the angle whose tangent is the given number parameter. This function works in a similar way to the Java Math function with the same name. The range of values returned by atan is between -pi/2 and pi/2 radians.
Parameter
number - A Number value.
Return value
Number value, which is an angle specified in number of radians.
Example
atan(1) - Returns an angle of 0.7854 radians (rounded to 4 radians). To convert this angle to degrees multiply by 180 / pi. For instance, atan (1) * 180 / pi is 45 degrees.