急求用MATLAB用龙格库塔和外推法解一阶微分方程

f=inline('-y+x+1','x','y'); %微分方程的右边项
dx=0.05; %x方向步长
xleft=0; %区域的左边界
xright=10; %区域的右边界
xx=xleft:dx:xright; %一系列离散的点
n=length(xx); %点的个数
y0=1;
%%(1)欧拉法
Euler=y0;
for i=2:n
Euler(i)=Euler(i-1)+dx*f(xx(i-1),Euler(i-1));
end
%%(2)龙格库塔法
RK=y0;
for i=2:n
k1=f(xx(i-1),RK(i-1));
k2=f(xx(i-1)+dx/2,RK(i-1)+k1*dx/2);
k3=f(xx(i-1)+dx/2,RK(i-1)+k2*dx/2);
k4=f(xx(i-1)+dx,RK(i-1)+k3*dx);
RK(i)=RK(i-1)+dx*(k1+2*k2+2*k3+k4)/6;
end
%%Euler和Rk法结果比较
plot(xx,Euler,xx,RK)
hold on
%精确解用作图
syms x
rightsolve=dsolve('Dy=-y+x+1','y(0)=1','x');%求出解析解
rightdata=subs(rightsolve,xx);%将xx代入解析解,得到解析解对应的数值
plot(xx,rightdata,'r*')
legend('Euler','Runge-Kutta','analytic')