(atan number1 [number2])
The atan function returns the arc tangent of an angle in radians.
If the second argument number2 is given, the function returns the arc tangent of number1 / number2 in radians.
If the argument number2 is zero, it returns an angle of 1.570796 radians.
The range of angles returned is -π/2 to +π/2 radians.
Examples
: (atan 0.8)
0.6747
: (atan -0.8)
-0.6747
: (atan 1)
0.7854
: (atan 1 3)
0.3218
: (atan -1 3)
-0.3218
Related Functions