Template for Kalman Filter implemented in Simulink Interpreted Function block

KF.m

function y = KF(x)
  % reference: https://www.mathworks.com/help/matlab/ref/persistent.html
  persistent A B C D dt m1 l1 R Q P0 P;

  % only executed at the first time -> initialization
  if isempty(P) 
    % A = ...; B = ...; C = ...; D = ...;
    % R = ...; Q = ...; P0 = ...;
    % m1 = ...; l1 = ...; dt = ...;
  end
  
  %% do KF 
  % Prediction
  % ...
  % Innovation
  % ...
end