Is there an atan2() function in KaleidaGraph?

The function below can be used to find atan2. The first line is a comment line, the second is the formula:

; atan2 function, must use radians!!
invtan2(a,b) =((a > 0)?invtan(b/a):((b<0)?invtan(b/a)-pi: invtan(b/a)+pi));

To add this function, choose Macros > Library and paste the definition on a new line in the library. You can then use invtan2() in a Formula Entry command, like c2=invtan2(c0,c1).