rong> the rotation
angle and <strong>w</strong> (3x1) the unit-vector indicating the rotation axis.

</p>
<p>
<strong>s</strong> = <span style="color:red">trlog</span>(<strong>T</strong>) is the matrix logarithm (4x4) of <strong>T</strong> (4x4)  which has a (3x3)
skew symmetric matrix upper left submatrix corresponding to the vector
<strong>theta</strong>*<strong>w</strong> where <strong>theta</strong> is the rotation angle and <strong>w</strong> (3x1) is a unit-vector
indicating the rotation axis, and a t