Need Help on matlab I did number one so I need help on numbe

Need Help on matlab!

I did number one, so I need help on number 2. Below is my code for number 1.

For basic model, substituting values for each parameter as given below. Fate of humanity after 20 weeks is shown in output.

a=0.005;

b=0.0095;

ze=0.0001;

d=0.0001;

T=20*7;

dt=1;

% This function will solve the system of ODE’s for the basic model used in

% the Zombie Dynamics project for MAT 5187. It will then plot the curve of

% the zombie population based on time.

% Function Inputs: a - alpha value in model: \"zombie destruction\" rate

% b - beta value in model: \"new zombie\" rate

%When Zombies Attack! 147

% ze - zeta value in model: zombie resurrection rate

% d - delta value in model: background death rate

% T - Stopping time

% dt - time step for numerical solutions

% Created by Philip Munz, November 12, 2008

%Initial set up of solution vectors and an initial condition

N = 500; %N is the population

n = T/dt;

t = zeros(1,n+1);

s = zeros(1,n+1);

z = zeros(1,n+1);

r = zeros(1,n+1);

s(1) = N;

z(1) = 0;

r(1) = 0;

t = 0:dt:T;

% Define the ODE’s of the model and solve numerically by Euler’s method:

for i = 1:n

s(i+1) = s(i) + dt*(-b*s(i)*z(i)); %here we assume birth rate

%= background deathrate, so only term is -b term

z(i+1) = z(i) + dt*(b*s(i)*z(i) -a*s(i)*z(i) +ze*r(i));

r(i+1) = r(i) + dt*(a*s(i)*z(i) +d*s(i) - ze*r(i));

if s(i)<0 || s(i) >N

break

end

if z(i) > N || z(i) < 0

break

end

if r(i) <0 || r(i) >N

break

end

end

hold on

plot(t,s,\'b\');

plot(t,z,\'r\');

legend(\'Suscepties\',\'Zombies\')

Solution

a=0.005;

b=0.0095;

ze=0.0001;

d=0.0001;

T=20*7;

dt=2;

N = 500;

n = T/dt;

t = zeros(2,n+1);

s = zeros(2,n+1);

z = zeros(2,n+1);

r = zeros(2,n+1);

s(2) = N;

z(2) = 0;

r(2) = 0;

t = 0:dt:T;

for i = 1:n

s(i+1) = s(i) + dt*(-b*s(i)*z(i));

z(i+1) = z(i) + dt*(b*s(i)*z(i) -a*s(i)*z(i) +ze*r(i));

r(i+1) = r(i) + dt*(a*s(i)*z(i) +d*s(i) - ze*r(i));

if s(i)<0 || s(i) >N

break

end;

if z(i) > N || z(i) < 0

break;

end;

if r(i) <0 || r(i) >N

break;

end;

end;

hold on

plot (t,s,\'b\');

plot (t,z,\'r\');

legend (\'Suscepties\',\'Zombies\');

end;