runge_kutta4.m

解线性方程组的Jacobi,Gauss_Seidel,SOR迭代

function[x,delta]=Runge_Kutta4(fun,x0,y0,N)
h=1/N;
x=zeros(1,N+1);
y=zeros(1,N+1);
delta(1)=0;
x(1)=x0;
y(1)=y0;
for n=1:N
    x(n+1)=x(n)+h;
    k1=h*feval(fun,x(n),y(n));
    k2=h*feval(fun,x(n)+1/2*h,y(n)+1/2*k1);
    k3=h*feval(fun,x(n)+1/2*h,y(n)+1/2*k2);
    k4=h*feval(fun,x(n)+h,y(n)+k3);
    y(n+1)=y(n)+1/6*(k1+2*k2+2*k3+k4);
end
for n=1:N
    delta(n+1)=abs(y(n+1)-x(n+1));
end
%plot(x,y,'b')
plot(x,delta,'r')