Steady states of graph

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Leah Powell
Leah Powell on 11 Apr 2015
Answered: Star Strider on 11 Apr 2015
I have produced numerical solutions for my system of ODE's in Matlab, and now I need to find their steady states which I can't figure out how to do.
My script is:
% DIFFERENTIAL EQUATION SYSTEM:
% dS/dt=μ-λSI-μS
% dI/dt=λSI-βI-μI
% dR/dt=βI-μR
% MAPPING: S = y(1), I = y(2), R = y(3)
SIR = @(t,y,mu,lam,b) [mu-(lam.*y(2)-mu).*y(1); (lam*y(1)-b-mu).*y(2); b*y(2)-mu*y(3)];
mu = 3; % mu
lam = 0.1; % lambda
b = 0.1; % beta
y0 = [2000; 0; 0];
tspan = linspace(0, 1, 100);
[T,Y] = ode45(@(t,y) SIR(t,y,mu,lam,b), tspan, y0);
figure(1)
plot(T, Y)
grid
legend('S(t)', 'I(t)', 'R(t)', 'Location', 'NW')
Could anyone tell me how to find the steady states/equlibrium points of my graph? I have tried right-clicking the graph but nothing comes up when I do. I am using Matlab R2011a.
Thanks :)

Answers (1)

Star Strider
Star Strider on 11 Apr 2015
I forgot to look at your initial conditions. With them, ‘S’ quickly goes to infinity, and the other two remain at zero.

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