function y=eulerpro(a,b,n,y0,f,f1,b1)
y=zeros(1,n+1);
y(1)=y0;
h=(b-a)/n;
x=a:h:b;
for i=1:n
T1=f(x(i),y(i));
T2=f(x(i+1),y(i)+h*T1);
y(i+1)=y(i)+(h/2)*(T1+T2);
end
plot(x,y);
hold on
x1=linspace(a,b,100);
'精确解为'
s=dsolve(f1,b1,'x')
syms x
y1=zeros(1,100);
for i=1:100
y1(i)=subs(s,x,x1(i));
end
plot(x1,y1,'r');
title('红色表示精确解')
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