SIR model parameter fitting

I want to find appropriate parameter i.e. beta.

First I have confirmed data for Jan.23~Dec.18.

I try to find best beta but result is same with inital guess beta. So I can't find how to do.

Here is my code.

I attach the data.

%% Data and current figure

clear; clc;

data_inc = readtable('inc_data2.csv','PreserveVariableNames',true);

date_inc = table2array(data_inc(:,1),'InputFormat','yyyy-MM-dd');

inc = table2array(data_inc(:,2));

% figure of incidence

figure(1)

bar(date_inc,inc)

%% data fitting

clc;

global beta gamma

beta = 0.01; gamma = 1/14;

parameter = [beta gamma];

IC1 = [880 10 0];

[t,y] = ode45(@SIR,[0,329],IC1);

plot(t,y);

%%

xdata = [1:1:329]';

ydata = inc;

x0 = parameter;

p = lsqcurvefit(@SIR,x0,[0,329],xdata,y,[0,0],[1,1]);

p

beta = 0.00001; % will change by lsqcurvefit result

gamma = 1/14;

IC2 = [beta gamma];

[t,y] = ode45(@SIR,[0,329],IC);

bar(xdata,inc)

hold on

plot(xdata,y(:,2));

hold off

%% plot

bar(xdata,inc)

hold on

plot(xdata,ydata,'r')

hold off

%% function

function dy = SIR(t,y)

global beta gamma

S = y(1); I = y(2);

dy = zeros(3,1);

dy(1) = -beta*S*I;

dy(2) = beta*S*I-gamma*I;

dy(3) = gamma*I;

end

Answer 1

[yeongju han]

Heejin, Can I ask u something?

How did you success this code..? I am studying the SEIRDV model considering the introduction of vaccines.

l want update 'beta' by using lsqcurvefit. But, I can't update 'beta'.. Can you review my code..? or,, Can you share me the complete code? I'm so desperate.

(I'm Korean, too ^_^)