SIS_System_Graph.svg


Summary

Description
English: Basic SIS system: dS/dt = -βIS/N + γI, dI/dt = βIS/N - γI

Initial Conditions: S(0) = 499, I(0) = 1

Parameters: β=0.001, γ=0.1, N=1, t∈[0,60], step size=0.5
Date
Source File:Sissys.png
Author https://commons.wikimedia.org/wiki/User:Bye~commonswiki

Graph generated from Mathematica

   Clear[IC, a, b, h, i, m, n, f, NN, β, γ];
   IC = {499, 1}; m = Length[IC];
   a = 0; b = 60; h = 0.5;
   NN = 1;
   n = (b - a)/h;
β = 0.001; γ = 0.1; f[1, t_, S_, I_] := -((β I S)/NN) + γ I; f[2, t_, S_, I_] := (β I S)/NN - γ I;
   Clear[t, k1, k2, k3, k4, w];
   t[i_] := a + i*h;
   For[i = 1, i <= m, i++, w[i, 0] = IC[[i]]];
   k1[i_, j_] := h*(f @@ Flatten[{i, t[j - 1], Table[w[k, j - 1], {k, 1, m}]}]);
   k2[i_, j_] := h*(f @@ Flatten[{i, t[j - 1] + h/2, Table[w[k, j - 1] + k1[k, j]/2, {k, 1, m}]}]);
   k3[i_, j_] := h*(f @@ Flatten[{i, t[j - 1] + h/2, Table[w[k, j - 1] + k2[k, j]/2, {k, 1, m}]}]);
   k4[i_, j_] := h*(f @@ Flatten[{i, t[j - 1] + h, Table[w[k, j - 1] + k3[k, j], {k, 1, m}]}]);
   w[i_, j_] := w[i, j] = w[i, j - 1] + (k1[i, j] + 2*k2[i, j] + 2*k3[i, j] + k4[i, j])/6
   t1 = Table[Table[{t[j], w[i, j]}, {j, 0, n}], {i, 1, m}](*//TableForm*);
   DkYellow = RGBColor[.808, .808, .192];
   Maroon = RGBColor[.5, 0, 0];
   ListPlot[t1, PlotMarkers -> {Automatic, Scaled[0.01]}, PlotStyle -> {DkYellow, Maroon}, AspectRatio -> 420/560]

Licensing

Creative Commons CC-Zero This file is made available under the Creative Commons CC0 1.0 Universal Public Domain Dedication .
The person who associated a work with this deed has dedicated the work to the public domain by waiving all of their rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law. You can copy, modify, distribute and perform the work, even for commercial purposes, all without asking permission.

Captions

Yellow=Susceptible, Maroon=Infected

Items portrayed in this file

depicts

1 April 2020

image/svg+xml