How can I check the parameters at each iteration in fminsearch

Hello everyone. I am very new in Matlab. I prepared a code that finds the minimum of RMSE to fit a data.

I have one function and also m file that calls function file. And easily trys to find the minimum. Please help me to prepare output file or change the option of fminsearch.

In order to save your time, I have copied my file here:

Thank you so much in advance.

Function File:

function [RMSE,Tfm_ILS] = Tfm_ILS(par,tau,Tfm_mis)
%   Detailed explanation goes here
T_0 = 15.96;                       % undisturbed ground temperature [°C]      
C_0 = 4900000;

r_bh = 0.076;                  % borehole radius [m]
a = par(1)/C_0;                 % 1st try thermal diffusivity [m2/s]
q = 110.22;

Tfm_ILS = T_0 + (q*par(2))+(q/(4*pi*par(1)))*(-0.5772 + log((4*a*tau)/(r_bh^2)));
RMSE=(sum((Tfm_ILS-Tfm_mis).^2)/length(tau))^0.5;
end

------------------------------------------------

M file is here:

load GHE1_6kW_P12_V1.txt
[min,n]=size(GHE1_6kW_P12_V1);
t_in=60;
t_end=1800;
tau = GHE1_6kW_P12_V1(t_in:t_end,1);
Tfm_mis = GHE1_6kW_P12_V1(t_in:t_end,2);
  
par = [8.7083, 0.0699];
options= optimset('OutputFcn', @outfun);

[RMSE,Tfm_ILS] = Tfm_ILS(par,tau,Tfm_mis);
[par,RMSE] = fminsearch('Tfm_ILS',par,options,tau,Tfm_mis);

[Walter Roberson]

You can add the option 'Display', 'iter' to optimset()

[Saeid Bina]

Thank you for your answer.

I add this, but only gives final results of function. While I would like to see the parameters at each iteration.

options= optimset('Display', 'iter');
[par,RMSE] = fminsearch('Tfm_ILS',par,options,tau,Tfm_mis);

[Walter Roberson]

By the way it is better to use

[par,RMSE] = fminsearch(@(par) Tfm_ILS(par,tau,Tfm_mis), par, options);

[Walter Roberson]

If you want to see the parameters at each iteration, put in a

disp(par)

in your Tfm_ILS function.

[Saeid Bina]

oh! Thank you so much for your great help!

I got them. Although they are a bit confusing but still good progress!

Iteration Func-count min f(x) Procedure

0 1 0.336821

9.1437 0.0699

8.7083 0.0734

1 3 0.336821 initial simplex

9.1437 0.0664

9.3614 0.0629

A little bit difficult to undrestand or export to Excel.

Thank you so much.

[Saeid Bina]

Above is just part of the iterations, I have coppied.