function y=Bern(i,n)
% 递归方法生成n阶Bernstein多项式的第i个函数

%  NUMERICAL METHODS: Matlab Programs
% (c) 2007 by Xie Liling
%  Complementary Software to accompany the textbook:
%  Information and Computing Science: A Laboratory Course

if i>n || i<1 
    y=0;
elseif i==1 && n==1
    y=1;
else 
    y1=conv(Bern(i,n-1),poly(1))*(-1);
    y2=conv(Bern(i-1,n-1),poly(0)); 
    r=length(y1);s=length(y2);
    if r>s y2=[zeros(1,r-s) y2]; end
    if r<s y1=[zeros(1,s-r) y1]; end
    y=y1+y2;
end