computing a regression polynomial of degree 2

I want to compute a regression polynomial for some datapoints and than estimate the value of the function at another datapoint!! i wrote something that gives me 0 error but the graph is not ok!! this is what i wrote

x= [0.9 1.5 2.4 2.6 2.8 3.1 3.5 3.8];    %Data points 
y= [1.0 0.8 1.3 6.2 9.3 6.0 2.1 -0.5];
p1 = polyfit(x,y,2);                     %The regression polynomial of degree 2
yest = polyval(p1,2.5);
xfit = linspace(0,length(x),8);
yfit = polyval(p1,xfit);
plot(x,y,'o',xfit,yfit,'-');
hold on 
p2 = polyfit(x,y,7);                     %The regression polynomial of degree 7
yest2 = polyval(p2,2.5);
xfit1 = linspace(0,10,8);
yFit1 = polyval (p2,2.5);
plot(x,y,'b',xfit1,yFit1,'--');
hold on 

[Torsten]

Set xfit = x and xfit1 = x instead of the linspace expressions.

[Anas Gharsa]

and now it gives me this

[Torsten]

You didn't substitute xfit1=x.

[Anas Gharsa]

Thank you so much !!!