Get rotation matrix from rotation axis and angle.

[n,rho] = rotmat2aqxi(R);

Given a rotation matrix R, the function rotmat2axi computes the rotation axis n and the angle of rotation rho around this axis defining the same rotation.

For details about rotation matrices, see the page on relative orientations.

rotmat2axi computes the components of the rotation axis vector directly from elements in the rotation matrix:

The rotation angle is given by

The following rotation matrix describes the interchange of the three principal axes of the coordinate system

R = [0 1 0; 0 0 1; 1 0 0]

R =
     0     1     0
     0     0     1
     1     0     0

Feeding this rotation matrix into rotmat2axi, we obtain the rotation axis and the rotation angle

[n,rho] = rotmat2axi(R)

n =
    0.5774
    0.5774
    0.5774
rho =
    2.0944

The rotation is 2π/3 around an axis pointing along the center of the first octant.

ang2vec, erot, rotaxi2mat, vec2ang