hbdevelop1

Hello,

I have noticed that the basic 3D rotation matrices in  http://en.wikipedia.org/wiki/Rotation_matrix

rotate vectors clockwise and not counter-clockwise, when the axis about which they occur points toward me !

For example: the following operation yields the vector (0,1,0)
[1      0      0     ]   [0]
[0  cos(90)  sin(90) ] X [0]
[0  -sin(90) cos(90) ]   [1]

Am I missing something ?

Thank you for your help

Hello,

With the two quaterions q1=q2=(cos theta/2, sin theta/2, 0, 0)
Does the product q1q2 yield a third quaternion q3 equals (cos theta, sin theta, 0, 0) ?

This is the result I am expecting to have from my quaternion class, but I don't have it.
My expectation is based on the fact that the concatenation of q1 and q2 will yield a quaternion representing both rotations. That means, for me, the sum of the angles each quaternion represents if the rotations are around the same vector.

So, does the product q1q2 yield a third quaternion q3 equal (cos theta, sin theta, 0, 0) ?
Or is there anything wrong with my assumption ?

Thank you in advance

Hello,

With the two quaterions q1=q2=(pi/8, 1, 0, 0)
Does the product q1q2 yield a third quaternion q3 equal (pi/4, 1, 0, 0) ?

This is the result I am expecting to have from my quaternion class, but I don't have it.
My expectation is based on the fact that the concatenation of q1 and q2 will yield a quaternion representing both rotations. That means, for me, the sum of the angles each quaternion represents if the rotations are around the same vector.

So, does the product q1q2 yield a third quaternion q3 equal (pi/4, 1, 0, 0) ?
Or is there anything wrong with my assumption ?

Thank you in advance