function a=SolveIFFL1
%% We define the parameters and their values
betay=1;
alphay=1;
betaz=1;
alphaz=1;
% Here are the parameters of the signal X:
x0=1;
x1=1;
%% We define the initial condition
y0=betay*x0/alphay;
z0=betaz/alphaz*alphay/betay;
% We call Matlab's ODE solver, to solve the dynamics of the vector Y 
% between time = 0 and time = 15, starting from the initial conditions at t=0.
[T,Y] = ode45(@(t,y) IFFL(t,y,x1,betay,alphay,alphaz,betaz), [0 15], [y0 z0]);
% We plot the dynamics and label the axes
figure;
plot(T, Y(:,2), '-');
xlabel('time');
ylabel('Z(t)');
end 
%% We define a function that returns the derivative of y where
% y is a vector of our two variables Y and Z.
function dy = IFFL(t,y,x1,betay,alphay,alphaz,betaz)
dy = zeros(2,1); 
dy(1) = betay*x1 - alphay*y(1); %this is the ODE for Y
dy(2) = betaz*x1/y(1) - alphaz*y(2); %this is the ODE for Z
end
