I want to round off my answer upto 4 decimal place but my code dosen't work.

function d=divided_diff(a,b,c,f1,f2,f3)
p=vpa((f2-f1)/(b-a));
q=vpa((f3-f2)/(c-b));
d=(q-p)/(c-a);
d=round(d,4);
end

[Walter Roberson]

What inputs are you using, and what problem are you observing?

[Aquatris]

Quick fix can be

round(double(d),4)