I need to obtain second derivativ Second derivative

I have a set of data as follows.

How can I calculate the second derivative of the curve obtained from these data.

x=[0.1;0.07;0.05;0.03;0]; 
r=[-98.9407;-105.7183;-111.2423;-116.0320;-120.0462];

Answer 1

[Azzi Abdelmalek]

y=gradient(gradient(r,x),x)

or

r1=diff(r)./diff(x)
r2=diff(r1)./diff(x(2:end))