function s2=xia5251(n);
x=[60 70 80 90 100 110 120 130 140 150 160 170];
y=[6.13 7.90 9.99 12.15 15.02 17.50 20.92 26.86 31.11 38.85 47.25 55.05];
plot(x,y,'*b');
hold on
[a,b]=xia3242(x,y,n);
s1=0;s2=0;
for i=1:12
    s1=s1+b(i);
end
s1=s1/12;
for i=1:12
    s2=s2+(b(i)-s1)^2;
end

%[a,b]=polyfit(x,y,n);
X=linspace(60,170,100);
Y=polyval(a,X);
plot(X,Y,'r');