1. Computational Mathematics Group, Rutherford Appleton Laboratory, Didcot OX11 0QX, UK.
2. Department of Computer Science, Wake Forest University, Winston-Salem, NC 27106 USA.
3. Department of Mathematics, Virginia Tech, Blacksburg, VA 24061-1026 USA.
4. Department of Mathematics, North Carolina State University, Raleigh, NC 27607 USA.
5. Department of Mathematics, Tufts University, Medford, MA 02155 USA.