function [yy1,r]=xia3242(x,y,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(xx);
for j=1:m;
    yy1(j)=xx(m-j+1);
end
for i=1:n;
    r(i)=y(i)-polyval(yy1,x(i));
end