I am running an optimization problem with MATLAB’s fmincon, and I get the error
**Error using saveOptimizationParams
Too many input arguments.
Error in sqpInterface
Error in fmincon (line 672)
`[X,FVAL,EXITFLAG,OUTPUT,LAMBDA,GRAD,HESSIAN] = sqpInterface(funfcn,X,full(A),full(B),full(Aeq),full(Beq), …
**

The problem is to minize obj = (alpha * populationDeviation) + (beta * locationDeviation);

The is is my optimization problem

cd('/main/path')
path2root= '/path/to/something/I need/';

% Load initial parameters from file
initial_params = readParameters('parameters.txt');

% Load target data from file
target_population = load('/path/to/targetPop.txt');

% Define optimization parameters
alpha = 1;  % Weight for population size deviation
beta = 1;   % Weight for location deviation




% Define the optimization problem
objFunction = @(params) objectiveFun(params, target_population,alpha,beta);
initial_guess = [initial_params.natural_growth_rate, initial_params.natural_death_rate ];
lb = [0, 0];
ub = [Inf, Inf];


options = optimoptions('fmincon', 'Display', 'iter', 'Algorithm', 'sqp','OutputFcn',  @saveOptimizationParams);
% Perform optimization
[opt_params, fval] = fmincon(@(params)objectiveFun(params, target_population,alpha,beta), initial_guess, [], [], [], [], lb, ub, [], options);

This is my objective function.

function obj = objectiveFun(params,target_population,alpha,beta)

    growth_rate = params(1);% Currently not used
    death_rate = params(2);% Currently not used

   % Read the optimized parameters to a new file
    initial_guess = readParameters('parameters.txt');

   %initial_guess=[initial_params.growth_rate,initial_params.death_rate];
   

    %Run ABM from jar fiel
    system( 'java -jar /path/to/file.jar/')



    % Load updated data from file
    current_population = readCurrentPop('/path/to/data.csv');

     
    % Calculate population deviation
    P_current = size(current_population, 1);
    P_target = size(target_population, 1);
    populationDeviation = (P_current - P_target)^2;



     % Calculate location deviation using the K nearest neigbor search
    [Idx, D] = knnsearch(target_population, current_population);
    locationDeviation=sum(D);
  

    % Calculate combined objective 
   obj = (alpha * populationDeviation) + (beta * locationDeviation);
   

end

And lastly this is my output function

function stop = saveOptimizationParams(optimValues, state)

    % File to write
    fileName = '/path/to/parameters.txt';

    % Initialize stop flag
     stop = false;

     

    % Check the state of the optimization
    switch state
        case 'iter'
            % Write the parameters to the file at each iteration
            currentParams = optimValues.x;
            paramCellArray = struct('natural_growth_rate', currentParams(1), 'natural_death_rate', ocurrentParams(2));
            writeParameters(fileName, paramCellArray);
    end
end

Tried: I checked that the objective function (objectiveFun), and the output function (saveOptimizationParams) run when by themselves when tested separately

The optimization also runs when I exclude the output function part from options, that is
options = optimoptions('fmincon', 'Display', 'iter', 'Algorithm', 'sqp');

However if I include the output function, the error occurs, even if the function is just dummy with nothing inside.
I use the output function to update my data at each step and so I want to run it at every iteration.

If anyone has any suggestion, or know what I am missing, I’d appreciated it. Thanks for reading