It looks like there are two parameters inside the atan function, but I'm not sure how to convert this to C#?
The IDL reference says "If two parameters are supplied, the angle whose tangent is equal to Y/X is returned. "
atan(out[2,*],sqrt(out[0,*]^2+out[1,*]^2))
atan(out[1,*],out[0,*])