怎么用龙格库塔法

初值给一下。
在Matlab下输入：edit，然后将下面两行百分号之间的内容，复制进去，保存
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
function dxdt=ode_Miss_ghost(t,x)
%分别用x(1),x(2),x(3),x(4)代替N1,P1,N2,P2
N1=x(1);
P1=x(2);
N2=x(3);