function QC = longleaf_quadrat(N,X,Y);
dX = 200/N;
X = X/dX;
Y = Y/dX;
X(find(X==0))=eps;
Y(find(Y==0))=eps;
QC = zeros(N);
for i=1:N
    for j=1:N
        QC(i,j) = length(find(ceil(X)==i&ceil(Y)==j));
    end
end