function [t,m]=xh(n)
%循环节的长度不会超过分母的值
l=floor(log10(n))+1;
m(1)=floor(10^l/n);
s(1)=mod(10^l,n);
for k=2:n;
m(k)=floor(s(k-1)*10/n);
s(k)=mod(s(k-1)*10,n);
if any(s(1:k-1)==s(k))
b=find(s(1:k-1)==s(k));
t=k-b;
break
end
end
m=num2str(m);
m=['0.',m(abs(m)~=32)];
m=[m(1:b+2),'(',m(b+3,end-1),')'];