拟合5种传染病模型matlab代码

以下是5种传染病模型的MATLAB代码示例：

### SIR模型代码

function SIRModel()
tspan = [0 100];
y0 = [0.99 0.01 0];
[t, y] = ode45(@sir, tspan, y0);
plot(t, y(:,1), 'r', t, y(:,2), 'g', t, y(:,3), 'b');
legend('Susceptible', 'Infected', 'Recovered');
title('SIR Model');
xlabel('Time');
ylabel('Population');

function dydt = sir(t, y)
beta = 0.2; % infection rate
gamma = 0.1; % recovery rate
S = y(1);
I = y(2);
R = y(3);
N = S + I + R;
dSdt = -beta*S*I/N;
dIdt = beta*S*I/N - gamma*I;
dRdt = gamma*I;
dydt = [dSdt; dIdt; dRdt];
end

end

### SEIR模型代码

function SEIRModel()
tspan = [0 100];
y0 = [0.99 0.01 0 0];
[t, y] = ode45(@seir, tspan, y0);
plot(t, y(:,1), 'r', t, y(:,2), 'g', t, y(:,3), 'b', t, y(:,4), 'm');
legend('Susceptible', 'Exposed', 'Infected', 'Recovered');
title('SEIR Model');
xlabel('Time');
ylabel('Population');

function dydt = seir(t, y)
beta = 0.2; % infection rate
sigma = 0.1; % incubation rate
gamma = 0.1; % recovery rate
S = y(1);
E = y(2);
I = y(3);
R = y(4);
N = S + E + I + R;
dSdt = -beta*S*I/N;
dEdt = beta*S*I/N - sigma*E;
dIdt = sigma*E - gamma*I;
dRdt = gamma*I;
dydt = [dSdt; dEdt; dIdt; dRdt];
end

end

### SIS模型代码

function SISModel()
tspan = [0 100];
y0 = [0.99 0.01];
[t, y] = ode45(@sis, tspan, y0);
plot(t, y(:,1), 'r', t, y(:,2), 'g');
legend('Susceptible', 'Infected');
title('SIS Model');
xlabel('Time');
ylabel('Population');

function dydt = sis(t, y)
beta = 0.2; % infection rate
gamma = 0.1; % recovery rate
S = y(1);
I = y(2);
N = S + I;
dSdt = gamma*I - beta*S*I/N;
dIdt = beta*S*I/N - gamma*I;
dydt = [dSdt; dIdt];
end

end

### SEIS模型代码

function SEISModel()
tspan = [0 100];
y0 = [0.99 0.01 0];
[t, y] = ode45(@seis, tspan, y0);
plot(t, y(:,1), 'r', t, y(:,2), 'g', t, y(:,3), 'b');
legend('Susceptible', 'Exposed', 'Infected');
title('SEIS Model');
xlabel('Time');
ylabel('Population');

function dydt = seis(t, y)
beta = 0.2; % infection rate
sigma = 0.1; % incubation rate
gamma = 0.1; % recovery rate
S = y(1);
E = y(2);
I = y(3);
N = S + E + I;
dSdt = gamma*I - beta*S*I/N;
dEdt = beta*S*I/N - sigma*E;
dIdt = sigma*E - gamma*I;
dydt = [dSdt; dEdt; dIdt];
end

end

### SIRS模型代码

function SIRSModel()
tspan = [0 100];
y0 = [0.99 0.01 0];
[t, y] = ode45(@sirs, tspan, y0);
plot(t, y(:,1), 'r', t, y(:,2), 'g', t, y(:,3), 'b');
legend('Susceptible', 'Infected', 'Recovered');
title('SIRS Model');
xlabel('Time');
ylabel('Population');

function dydt = sirs(t, y)
beta = 0.2; % infection rate
gamma = 0.1; % recovery rate
mu = 0.01; % immunity loss rate
S = y(1);
I = y(2);
R = y(3);
N = S + I + R;
dSdt = mu*R - beta*S*I/N;
dIdt = beta*S*I/N - gamma*I;
dRdt = gamma*I - mu*R;
dydt = [dSdt; dIdt; dRdt];
end

end

这些代码示例可以用来模拟传染病的传播和控制，但需要根据实际情况进行调整和优化。