hello everyone, I have problem in my project written by matlab to solving my equations with rang-kuta 4 order method. I send my project file.  please help me to run it correctly. thank you.

input Q_j n j V Z F_ve a_1 a_2 p_1 p_2 L A f m k c h t i;

for jj=1:n;

            s=Q_j(jj);

end

b=(-V)*Z;

o=(F_ve*A)*(((a_1^2)*p_1)-((a_2^2)*p_2))/L;

% RK4 method;

% md2z/dt2+cdz/dt+kz=f;

% dz_1/dt=z_2;

% mdz_2/dt+cdz_1/dt+z_1k=f;

% dz_2/dt=1/m(f-cz_2-kz_1);

f=0;

m=1;

k=s+b+o;

c=0;

h=0.5;

t=0:0.5:t;

z1=zeros (1,n);

z2=zeros (1,n);

z1 (1)=0;

z2 (1)=1;

% N=length (t);

f1=@(t,z1,z2)z2;

f2=@(t,z1,z2)f-(c*z2)-(k*z1);

for i=1:n-1;

    k1=f1 (t (i),z1 (i),z2 (i));

    m1=f2 (t (i),z1 (i),z2 (i));

    k2=f1 (t (i)+h/2,z1 (i)+0.5*k1*h,z2 (i)+0.5*m1*h);

    m2=f2 (t (i)+h/2,z1 (i)+0.5*k1*h,z2 (i)+0.5*m1*h);

    k3=f1 (t (i)+h/2,z1 (i)+0.5*k2*h,z2 (i)+0.5*m2*h);

    m3=f2 (t (i)+h/2,z1 (i)+0.5*k2*h,z2 (i)+0.5*m2*h);

    k4=f1 (t (i)+h,z1 (i)*k3*h,z2 (i)*m3*h);

    m4=f2 (t (i)+h,z1 (i)*k3*h,z2 (i)*m3*h);

    z1 (i+1)=z1 (i)+(h/6)*(k1+(2*k2)+(2*k3)+k4);

    z2 (i+1)=z2 (i)+(h/6)*(m1+(2*m2)+(2*m3)+m4);

end

plot (t,z1)

plot (t,z2)

plot (z,t)