han 0.01,
  <LI> use a 3rd order taylor series approximation to the exponential,
  <LI> repeatedly square the result to undo the scaling, and 
  <LI> if the largest element of the original was greater than 0.001
       apply one iteration of a quadratically convergent symmetric
       orthogonalization (two matrix multiplications).
</OL>
This is tailored to the antisymmetric matrices typical of our
applications and may not be stable for more general matrices.

 <P>The net result is that in a typical calcula