Arguments

num1  a number (integer or double)

num2  (optional) a number (integer or double)

Return

arctangent in radians (double);
the result is in [-PI/2,+PI/2] range; with num2 used, result is in [-PI,PI]

Example

(atan 2)
1.10714871779409

(atan 2 4)
0.463647609000806

(atan 2.0)
1.10714871779409

(atan 2 -4.0)
2.67794504458899

Remarks

if num2 is 0, the result is +/-1.5707963267949 radians (+/-90 degrees)