Hello,
To my understanding, your code should be like as shown below
clc,
clear,
close all
modelfun= @(b,x)(b(1)+b(2)*exp(-b(3)*x));
x=[0;0.5;1;1.5;2;2.5;3;3.5;4;4.5;5];
y=[0; 0.223904; 0.323333; 0.372308; 0.359143; 0.332033; 0.278462; 0.243394; 0.232222; 0.198334; 0.173414];
b = 0:0.01:5;
[beta, R, J] = nlinfit(x, y, modelfun,b);
Hope it helps
