clear all
A=[0 1.1;0.55 0.55]
y=zeros(2,20);    %build a matrix to store the population data
t=zeros(1,20);    %build a matrix for total population
y(:,1)=[200;0];  %initialize
t(1,1)=sum(y(:,1)); %initialize the sum
for n=1:19
    y(:,n+1)=A*y(:,n);   %update with matrix model
    t(1,n+1)=sum(y(:,n+1));  %update the sum
end
plot([1:20],y(1,:),'*r',[1:20],y(2,:),'xb',[1:20],t(1,:),'og')
legend('juveniles','adults','total')