Question about angles

[atamasan]

Hello. I've written some questions and got many useful comments here, thanks a lot.

I have a question about angle.
Now, I am trying to get angle between 2 bones of 'hand.cfg'.
Especially, I want to get angle between 'bone little 4-0' and 'bone little 4-1' when grabbing object.

To do this, I'm using 'vizmat.QuatDiff' now.

bone1=hand.getBone('bone little 4-0')
bone2=hand.getBone('bone little 4-1')
bone1,bone2.lock()
.
.
.
print vizmat.QuatDiff(bone1.getQuat(),bone2.getQuat())

I could get a angle by this code. But I don't know if this code is wrong or not.
note:I want to know angle along Y AXIS in bone2's PARENT COORDINATE SYSTEM because this is main angle when human's hand grab something.

Should I use AxisAngle or something?
Please give me some advice and I am sorry for my English everytime.