 <li>If theta is given then the first argument must be a unit vector or a
skew-symmetric matrix from a unit vector.</li>
  <li>Angle vector argument order is different to ANGVEC2R.</li>
</ul>
<h2>References</h2>
<ul>
  <li>Robotics, Vision & Control: Second Edition, Chap 2,
P. Corke, Springer 2016.</li>
  <li>"Mechanics, planning and control"
Park & Lynch, Cambridge, 2017.</li>
</ul>
<h2>See also</h2>
<p>
<a href="angvec2r.html">angvec2r</a>, <a href="trlog.html">trlog</a>, <a href="trexp2.html">trexp2</a>,