function B=merge_func(A)
%合并排序(merge sort)算法
B=A;
n0=length(A);
n1=floor(n0/2);
n2=n0-n1;
A1(1:n1)=A(1:n1);
A2(1:n2)=A(n1+1:n0);
if n1>1
A1=merge_func(A1);
end
if n2>1
A2=merge_func(A2);
end
A1(n1+1)=1e20;
A2(n2+1)=1e20;
i=1;
j=1;
for k=1:n0
if A1(i)<A2(j)
B(k)=A1(i);
i=i+1;
else
B(k)=A2(j);
j=j+1;
end
end
