function [ x f ] = hourglass( a, x0, x1, m, n )
%HOURGLASS Summary of this function goes here
%   Detailed explanation goes here

    % The difference equation for the hourglass attractor
    f=@(p,q) q.*(a-p.^2);
    
    % Run off the first m terms
    for j=1:m
        x = f(x0,x1);
        x0=x1;
        x1=x;
    end
    
    % Store the last n terms of the sequence
    x = zeros(1,n);
    x(1) = x0;
    x(2) = x1;
    
    % Fill in the tail
    for j = 3 : n
        x(j) = f(x(j-2),x(j-1));
    end

end