I am solving a quadratic interpolation on matlab and i need a bit help

I solved this quadratic equation and i want to program it on matlab..here is the code xB=[-1.6 7.6 15.4 26.1 42.2 60.6];

yB=[20 40 60 100 200 400];

xxB=25;

n=length(xB)

if length(yB)~=n, error('x and y must be the same length');

end

D=0;

for i=1:n;

    product=yB(i);

    for j=1:n

        if i~=j

            product=product*((xxB-xB(j))/(xB(i)-xB(j)))*((xxB-xB())/(xB(i)-xB()));
        end
    end
    D=D+product;
end
yBint= D

when i put j in the bracket for the xxB-xB().. it didnt give me the right answer. should i add a new variable e.g k ?

[Star Strider]

What do you want to do? I don’t see the parallels between the JPG image (that is difficult to read) and your code.

[Mike Garret]

i was given a table of values and i want to find what what the pressure is at 25 degrees...i have attached the original question..it is problem b