Lagrange's interpolation

function p = lagrange_interpolation(x, y)
    n = length(x);
    p = 0;
    for i = 1:n
    L = 1;
        for j = 1:n
            if( i ~= j)
                L = conv(L, [1 -x(j)])/(x(i)-x(j));
            end
        end
        p = p + y(i)*L;
    end
end