f_gradient =
TT=[1 1 1 1];
noise = randi([2 10]);
syms p0 p1 p2 p3 p4;
f_function = log(noise+p1*TT(1)+p2*TT(2)+p3*TT(3)+p4*TT(4));
f_gradient = gradient(f_function,[p0, p1, p2, p3, p4])
f_gradient = double(subs(f_gradient,{p1,p2,p3,p4},{2,2,1,4})) % give some values and use subs