function [t,NN,air,U,UVDOT,VVDOT, summ]=coup(order,kappa)%,rinitial)
tic

numBr = 2^order - 1;     % number of airways
numOrd1 = (numBr+1)/2;
% initial values for airways (mm)
rimax = [0.296 0.318 0.337 0.358 0.384 0.414 0.445 0.484 0.539 0.608 ...
    0.692 0.793 0.913 1.052 1.203 1.374];
rinitial=[];
for k=1:order
    rinitial=[rinitial;rimax(k)*ones(2.^(order-k),1)];
end
rinitial=rinitial+0.01*rand(1,length(rinitial))'; % peturbation of rinitial

r(:,1)=rinitial; %airways, order 1 : order n
uv(:,1) = zeros(numBr,1); % pressure in airway
vv(:,1) = zeros(numBr,1); % airflow within the airway
vds(:,1) = zeros((numBr+1)/2,1); % airflow entering alveoli

y0 = [r(:,1); uv(:,1); vv(:,1); vds(:,1)]; %ICs vector

    parm = [kappa];
    tspan = [0 80];

    % Set numerical accuracy options for ODE solver
    options = odeset('RelTol', 1e-08, 'AbsTol', 1e-08, 'MaxStep', 0.01);
    
    [t,NN]=ode15s(@(t,y) seven_airway(t,y,order,parm), tspan, y0, options);
    U = zeros(length(NN),length(r)); % pressure including viscous damping
    UVDOT = zeros(length(NN),length(r));
    VVDOT = zeros(length(NN),length(r)); %airflow
    VVDOT = zeros(length(NN),length(r)); %airflow
    for j = 1:length(NN)
        [U(j,:),UVDOT(j,:),VVDOT(j,:)] = seven_airway2(t(j),NN(j,:),order,parm);
    end
toc
CM=jet(length(rinitial));
r_new = NN(:,1:numBr);

for i=1:length(rinitial)

   if r_new(end,i) <= 0.01
       air(i)=0;
   else
       air(i)=1;
   end

end
% for i = 1:length(rinitial)
%     figure(1)
%     plot(t,r_new(:,i),'-','color',CM(i,:),'LineWidth', 1.5, 'MarkerSize', 8);
%     hold on
% 
% end
% % %     
% % %     
% legendStr = cell(1,length(rinitial));
% for i = 1:length(legendStr)
%     legendStr{i} = sprintf('r_{%d}',i);
% 
% end
% legend(legendStr,'Location','BestOutside');
%% Measure for state of heterogeniety
x = cell(1,numOrd1);
for i = 1:length(x)
    x{i} = air(i);
end
summ = zeros(1,length(x{1}));
for i = 1:length(x)
    switch i
        case 1
            neighbour_diff = sqrt((x{i} - x{end}).^2 + (x{i} - x{i+1}).^2);
        case length(x)
            neighbour_diff = sqrt((x{i} - x{i-1}).^2 + (x{i} - x{1}).^2);
        otherwise
            neighbour_diff = sqrt((x{i} - x{i-1}).^2 + (x{i} - x{i+1}).^2);
    end
    summ = summ + neighbour_diff;
    
end
summ=summ./(2^(order-3)*4*sqrt(2));
% %% graphing airways
% node1 = zeros(1,numBr);
%     node2 = zeros(1,numBr);
%     
%     % e.g. for an order 4: node1 = [1 2 2 3 3 4 4 5 5 6 6 7 7 8 8];
%     node1(1) = 1;
%     for i = 1:(numBr-1)/2
%         node1(2*i:2*i+1) = [i+1 i+1];
%     end
%    
%     % e.g. for an order 4: node2 = [2 3 4 5 6 7 8 9 10 11 12 13 14 15 16];
%     for i = 1:numBr
%         node2(i) = i+1;
%     end
%     
%     ind = zeros(1,numBr);
%     for i = 1:numBr
%         ind(i) = i;
%     end
%     figure,
%     A=[fliplr(air)];
%     
%     G = graph(node1,node2,A);
%     h=plot(G,'LineWidth',2);
%     h.EdgeCData=A;
%     labelnode(h,[node1 node2],'')
%     labeledge(h,ind,G.Edges.Weight(ind));
%     colormap jet