function yy1=xia324(x,y,xx1,s)
n=length(x);
A=ones(1,n);
for i=1:s;
    A=[A;x.^i];
end
xx=inv(A*A')*A*y';
m=length(xx1);
yy1=zeros(1,m);
for j=1:(s+1);
    yy1=yy1+xx(j)*xx1.^(j-1);
end