c = [0.05; 0.1; 0.2; 0.4; 1];
obs = [3.947; 4.314; 4.171; 4.149; 4.109];
% Create a 3-D optimization variable named 'k'.
k = optimvar('k',3);
% Create an optimization problem named prob having obj as the objective function.
fun=@(k) func(k,c,obs);
prob = optimproblem('Objective',fcn2optimexpr(fun,k));
% Solve Problem
k0.k = [1.48 5E-4 4.01E-08];
[sol,fval,exitflag,output] = solve(prob,k0);
function obj=func(k,c,obs)
% To obtain the objective function
c_plus = (-k(1) + ((k(1).^2)-8*(-c*k(1))).^0.5)/4;
D = (c(:) - c_plus(:))/2;
est = k(2)*c_plus./(1+D./k(3)); % this line causes the problem
% Create the objective function
obj = sum((obs - est).^2);
end
