function h = avestr(A)
[m,m] = size(A);
h = 0;
for i=1:m
  for j=i+1:m
    x = A(:,i);
    y = A(:,j);
    d = sum(abs(x-y));
    h = h + d;
  end
end
h = h / (m*(m-1));
return