[Scilab-users] Corona modelling

[Stéphane Mottelet]

Hello Heinz,

Here is an interactive version (made for my children last week...) :

// Confinement COVID-19 !
// Stephane MOTTELET, UTC
// Tue Mar 24 08:55:03 CET 2020
//
function  dydt=sir(t, y, bet, gam, N)
     dydt=[-bet/N*y(1)*y(2)
            bet/N*y(1)*y(2)-gam*y(2)   
            gam*y(2)];
endfunction

function  draw(bet, gam)
     t=0:1:360;
     N=6e7;
     if  exists("gcbo")  &&  is_handle_valid(gcbo)
         sb  =  gcbo;
         if  sb.tag=="beta"
             bet=sb.value;
             gam=findobj("gamma").value
         else
             gam=sb.value;
             bet=findobj("beta").value
         end
         y=ode('stiff',[N-1;1;0],0,t,list(sir,bet,gam,N));
         curves  =  findobj("curves");
         curves.children(1).data(:,2)=y(3,:);
         curves.children(2).data(:,2)=y(2,:);
         curves.children(3).data(:,2)=y(1,:);
     else
         y=ode('stiff',[N-1;1;0],0,t,list(sir,bet,gam,N));
         scf(0)
         clf
         plot(t,y)
         gce().tag="curves";
         gce().children.thickness=2;
         legend("Susceptible","Infected","Recovered",-1)
         
         sb1  =  uicontrol("style","slider",...
         "units","normalized",...
         "Position",  [0.85,0.2,0.05,0.48],...
         "BackgroundColor",  [1,1,1],...
         "Callback_Type",12,...
         "sliderstep",[1/1000,1/10],...
         "min",0.15,"max",0.3,"value",bet,...
         "Callback","draw","tag","beta");
         
         uicontrol("style","text",...
         "string","$\beta$",...
         "units","normalized",...
         "Position",  [0.85,0.125,0.05,0.08],...
         "BackgroundColor",  [1,1,1],...
         "HorizontalAlignment","center");         
         
         sb1  =  uicontrol("style","slider",...
         "units","normalized",...
         "Position",  [0.90,0.2,0.05,0.48],...
         "BackgroundColor",  [1,1,1],...
         "Callback_Type",12,...
         "sliderstep",[1/1000,1/10],...
         "min",0,"max",1/15,"value",gam,...
         "Callback","draw","tag","gamma");

         uicontrol("style","text",...
         "string","$\gamma$",...
         "units","normalized",...
         "Position",  [0.9,0.125,0.05,0.08],...
         "BackgroundColor",  [1,1,1],...
         "HorizontalAlignment","center");         

     end
end

clf

draw(0.3,1/15)

Le 30/03/2020 à 02:14, Heinz Nabielek a écrit :
> Colleagues:
>
> is there an straightforward Scilab approach for solving the three coupled nonlinear differential equations of first order given by the Standard Model of Epidemics?
>
>
> S= number Susceptible: 		S'=-aSI
> I=  number Infected:		I'=aSI - bI
> R= number Recovered: 		R'=bI
> whereby 'a' is the transmission coefficient, 'b' the recovery factor (after Reed-Frost 1928).
> Initial values for S, I, R are available.
>
> Thank you
> Heinz
> _______________________________________________
> users mailing list
> users at lists.scilab.org
> https://antispam.utc.fr/proxy/1/c3RlcGhhbmUubW90dGVsZXRAdXRjLmZy/lists.scilab.org/mailman/listinfo/users

-- 
Stéphane Mottelet
Ingénieur de recherche
EA 4297 Transformations Intégrées de la Matière Renouvelable
Département Génie des Procédés Industriels
Sorbonne Universités - Université de Technologie de Compiègne
CS 60319, 60203 Compiègne cedex
Tel : +33(0)344234688
http://www.utc.fr/~mottelet

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.scilab.org/pipermail/users/attachments/20200330/5b73f1e6/attachment.htm>