function  sol = coefficient(x,D)

     dim = size(D);
     n = dim(1)   ;
     
     a = x;
     b = D;



for i = 1:n-1
     tempc(i) = 3*(x(i+1) - x(i)) - 2*D(i) - D(i+1);
     tempd(i) = 2*(x(i) - x(i+1)) + D(i) + D(i+1);
end

     tempc(n) = 3*(x(1)-x(n)) - 2*D(n) - D(1);
     tempd(n) = 2*(x(n) - x(1)) + D(n) + D(1);

c = tempc';
d = tempd';


sol = [d c b a];