Dear Allstaters, This morning I am overwhelmed with replies to my query Many thanks to: Andrew Metcalfe, Jonathan Myles, Nigel Stannard, Peggo Lam, David Chan, Derek Christie, Miland Joshi, Tim Auton, Pat Gaffney, Scott Chasalow, David Woof, Emma McCoy, Gerda Arts, And lots more Meanwhile, I dreamed. My dream told me to re-arrange the problem. I woke at three. My dream had told me to re-arrange the matrix J=1 J=2 J=3 J=4 I=1 1 2 4 I=2 3 5 I=3 6 I=4 The solution is independent of N: 1 + I -1.5*J +0.5*J*J Allstat is wonderful. -- Tony Greenfield Middle Cottage Little Hucklow Derbyshire SK17 8RT 01298 872326 www.greenfield.org.uk %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%