clear all, close all
% Input data and other problem dependent functions and parameters.
xvec = [0:1:11]';
yvec = [260 992 2717 5341 8224 13195 21355 32196 35230 43352 45524 47572]';
b_0 = [yvec(1), max(yvec), 1]';

% use analytic solution
format long g;
b_opt = nlinfit(xvec,yvec,@logistic,b_0)

% use numerical solution
b_opt = nlinfit(xvec,yvec,@num_logistic,b_0)