Lorenz equation with 4th rungekutta method

I would like to plot the Lorentz equation using 4th rungekutta method.(If possible don't use ODE)
Please give me how to plot it.
for loop seems difficult and i don't understand.
    
dy/dt=-xz+rx-y
dz/dt=xy-bz      p=10,　r=28,　b=8/3
x(0)=10, y(0)=12, z(0)=25ing the 

x(1)=10;
y(1)=12;
z(1)=25;
dy(1)=p*y(1)+p*y(2);
dy(2)=-y(1)*y(3)+r*y(1)-y(2);
dy(3)=y(1)*y(2)-b*y(3);
for i=1:length(t)-1;
　　 y(i+1)=y(i)+v(i)*h
  
   i don't know following.