In OSL we have a rotate function,

"point rotate (point Q, float angle, point P0, point P1) Returns the point computed by rotating point Q by angle radians about the axis that passes from point P0 to P1."

but I cannot find an equivalent function in ai_vector.h that would enable me to rotate a AtVector.

I looked at ai_matrix.h in the hope of finding a function or functions that I might use but without any luck. Do you have any suggestions?