rotm = quat2rotm(quat) converts
a quaternion quat to an orthonormal rotation
matrix, rotm. When using the rotation matrix,
premultiply it with the coordinates to be rotated (as opposed to postmultiplying).
Unit quaternion, specified as an n-by-4 matrix or
n-element vector of quaternion objects containing
n quaternions. If the input is a matrix, each row is
a quaternion vector of the form q = [wxyz], with w as the scalar
number.
Rotation matrix, returned as a 3-by-3-by-n matrix
containing n rotation matrices. Each rotation matrix
has a size of 3-by-3 and is orthonormal. When using the rotation matrix,
premultiply it with the coordinates to be rotated (as opposed to postmultiplying).