function d = RD_2nd_deriv_cubic(y,h)
%

num_pts = length(y);
d = zeros(1,num_pts);
for p = 1:num_pts-3
    d(p) = (-y(p+3) + 4*y(p+2) - 5*y(p+1) + 2*y(p))/h^2;
end
