function A = divdifs(DA)
%this function calculates the divided diff table for DA;
%DA is the n,2 input data;
%A is the vector of coef of the Newton Form;
[n,m] = size(DA);
D=zeros(n,n); D(:,1)= DA(:,2);
X=DA(:,1);
for j=2:n
    for i=j:n
        D(i,j)= (D(i,j-1)-D(i-1,j-1))/(X(i)-X(i-j+1));
    end
end
%D
A=diag(D);