[ODE] dAMoterUser , angle between to vectors and possible winding problem

[jnilson_99 at yahoo.com]

Could someone look at the following url and tell me if
it's an adequate way to find the angle between two
vectors for use by dJointSetAMotorAngle.

www.jtaylor1142001.net/calcjat/Solutions/VDotProduct/VDPTheta3D.htm

i'm using a ball and socket with an amotor in
dAMotorUser mode. when i use the "classic" method
above for finding the angle between two vectors(i.e.
the x,y,z axis of the body and world rotation
matrixes), my joint flips out.

which makes me think maybe i'm not including "winding"
order into the angle information. is this important
for getting the correct angle to send to ode?

thanks,

john