x0=0.7;
y0=0.2;
a=1.24; %1..1.25, 1.4
b=0.1;   %0.3
n=1000;
f = @(x,y) 1+y-a.*x^2;
x=[x0;y0];
for k=1:n 
    x=[x,[f(x(1,end),x(2,end));b.*x(1,end)]];
end;
figure(1)
plot(x(1,400:n),x(2,400:n),'r.','MarkerSize',5)