function varargout=saxplaxliu(varargin)
clc,clear
x0=0;xn=5;y0=1;h=0.1;
[y,x]=lgkt4j(x0,xn,y0,h);
n=length(x);
gg=0:0.1:5;
ff=exp(gg);
plot(x,y,'o--g',gg,ff,'r')
function z=f(x,y)
z=y;
function [y,x]=lgkt4j(x0,xn,y0,h)
x=x0:h:xn;
n=length(x);
y1=x;
y1(1)=y0;
for i=1:n-1
K1=f(x(i),y1(i));
K2=f(x(i)+h/2,y1(i)+h/2*K1);
K3=f(x(i)+h/2,y1(i)+h/2*K2);
y1(i+1)=y1(i)+h/3*(K1+K2+K3);
end
y=y1;
