cost_func.m

function e = cost_func(param, mode, data)
% COST_FUNC calculates the error between experimental and simulated cytokine concentrations

e = [];
for i = 1:length(mode)
    x = mode(i);

    % Retrieve experimental data
    [t, TNF, IL6, IL10, IL1, ~, Temp, BP, HR, ~, corrTNF, corrIL6, corrIL10] = data_model(x, data);

    % Simulate cytokine concentrations
    [tsim, ysim] = model_code(x, param, 0, 0, 0, Temp(1), BP(1), HR(1));

    % Interpolate simulated cytokine concentrations to match experimental time points
    TNF_simulated = interp1(tsim, real(ysim(:,5)), t, 'spline');
    IL6_simulated = interp1(tsim, real(ysim(:,7)), t, 'spline');

    % Calculate squared error for TNF and IL6
    TNFerror = corrTNF * ((TNF - TNF_simulated) ./ max(TNF)).^2;
    IL6error = corrIL6 * ((IL6(1:7) - IL6_simulated(1:7)) ./ max(IL6)).^2;

    % Calculate error for IL10 if available
    if corrIL10 == 1
        IL10_simulated = interp1(tsim, real(ysim(:,9)), t, 'spline');
        IL10error = corrIL10 * ((IL10 - IL10_simulated) ./ max(IL10)).^2;
        e = [e; TNFerror; IL6error; IL10error];
    else
        e = [e; TNFerror; IL6error];
    end
end
end