Runga Kutta Mthod 4

I want to solve second order equation through Ruga kutta method .Please check what is error in this code

%input paramters

m=100;

k=25000;

e=100;

F=15000;

w=(k/m)^0.5;

t(1)=0;

x(1)=0;

v(1)=1;

h=0.1;

tfinal=100;

N=ceil((tfinal-t(1))/h);

f1=@(t,x,v) v;

f2=@(t,x,v) -(k/m)*v-(e/m)*x+(F/m)*cos(w*t);

for j=1:N;

t(j+1)=t(j)+h;

K1x=f1(t(j),x(j),v(j));

K1v=f2(t(j),x(j),v(j));

K2x=f1(t(j)+h/2,x(j)+h/2*K1x,v(j)+h/2*K1v);

K2v=f2(t(j)+h/2,x(j)+h/2*K1x,v(j)+h/2*K1v);

K3x=f1(t(j)+h/2,x(j)+h/2*K2x,v(j)+h/2*K2v);

K3v=f2(t(j)+h/2,x(j)+h/2*K2x,v(j)+h/2*K2v);

K4x=f1(t(j)+h,x(j)+h*K3x,v(j)+h*K3v);

K4v=f2(t(j)+h,x(j)+h*K3x,v(j)+h*K3v);

x(j+1)=x(j)+h/6*(K1x+2*K2x+2*K3x+K4x);

v(j+1)=v(j)+h/6*(K1v+2*K2v+2*K3v+K4v);

end

disp(x(N));

figure;

plot(t,x,'lineWidth',1);

Answer 1

[Alan Stevens]

As before, your value for h is too large. Set h = 0.01 and it works!