When I plot f towards time amplitude is increasing I don't know why. It should be constant. what's wrong?

f(1)=10;    %% Ratation angle (Rad)
w(1)=0;    %% Angular velocity (Rad/sec)
E(1)=0;    %% Angular acceleration

t(1)=0;    %% Time vector (sec)
dt=0.001;

N=10000;
%% The main code
for i= 1:N
    t(i+1)=t(i)+dt;
    
    E(i)=-f(i); 
    w(i+1)=w(i)+E(i)*dt;
    f(i+1)=f(i)+w(i)*dt;
end
plot(t,f);

Answer 1

[Matt J]

I don't see why f should be constant, but nor is it monotonically increasing. Once I fix your initialization code, I see a sine-like wave:

clear

N=10000;

[f,w,E,t]=deal(zeros(1,N));

f(1)=10;
dt=0.001;


%% The main code
for i= 1:N
    t(i+1)=t(i)+dt;
    
    E(i)=-f(i); 
    w(i+1)=w(i)+E(i)*dt;
    f(i+1)=f(i)+w(i)*dt;
end
plot(t,f);

[Nikoloz Nikuradze]

Yes but the amplitude of this wave is increasing if try N=10000000

[Matt J]

Perhpas you meant to have,

 f(i+1)=f(i)+w(i+1)*dt;

[Nikoloz Nikuradze]

You are right that helped a lot. Thank you