function s=traprl
%區(qū)間逐次分半的復化梯形計算積分
a=0;
b=1;
m=0;
z=0;
T=(b-a)/2*(exp(-a^2)+exp(-b^2));
while 1
    t=T;
h=(b-a)/2^(m+1);
for i=1:2^m
    c(i)=a+(2*i-1)*h;
    d(i)=exp(-c(i)^2);
end
for j=1:2^m
    z=z+d(i);
end
    T=0.5*T+h*z;   
if abs((T-t)/T)<10e-4                    
  break;
else
    m=m+1;
    z=0;
end
end
Sum=2^m; 
m                              
T