How to add value to matrix?

I want to add elements to matrix.

I want to add the calculated value to the end.　In the code below, I would like to add the calculated value of R to RR.

I tried R = []; RR (end + 1) = R ;, but only one value was added.

I want to add all the R calculated in one simulation to the RR.(R is one value.)

% Define of step function at each step in reinforcement learning
function [NextObservation, Reward, IsDone, LoggedSignals] = myStepfunction(Action,LoggedSignals,SimplePendulum)

      
        
        statePre = [-pi/2;0];
        statePre(1) = SimplePendulum.Theta;
        statePre(2) = SimplePendulum.AngularVelocity;
        
        IsDone = false;
       
       
        SimplePendulum.pstep(Action);
        
       
        state = [-pi/2;0];                                
        state(1) = SimplePendulum.Theta;                
        state(2) = SimplePendulum.AngularVelocity;     
        
        X_state_Position = sin(state(1));
        Y_state_Position = -cos(state(1));
        
        
        
        RR = [];
        R = ones(1,1);
       
        Ball_Target = 10;
        Ball_Distance = X_state_Position + (-state(2))* sqrt(2*abs(Y_state_Position)/9.8);
       
       
        R =  -abs(Ball_Distance -Ball_Target);
        RR(end+1) = R;　
      
         
         if (state(2) > 0) ||  (SimplePendulum.Y_Position < 0) 
             IsDone = true;
             
             [InitialObservation, LoggedSignal] = myResetFunction(SimplePendulum);
              LoggedSignal.State = [-pi/2 ; 0];
              InitialObservation = LoggedSignal.State;
              state = InitialObservation; 
              SimplePendulum.Theta =-pi/2;
              SimplePendulum.AngularVelocity = 0;
             
         
         end
          
      
        
      
        LoggedSignals.State = state;                  
       
        
      
        NextObservation = LoggedSignals.State;
          
       
        Reward =  +R;
            
        
            
  
end

[KSSV]

There is no loop why you want to use end+1 or indexing?

[ryunosuke tazawa]

I tried to use for loop.

But reslut was -4.4274 -4.4274 -4.4274 -4.4274 -4.4274 -4.4274 -4.4274 -4.4274 -4.4274 -4.4274 -4.4274 -4.4274 -4.4274 -4.4274 -4.4274 -4.4274 -4.4274 -4.4274 -4.4274 -4.4274 -4.4274 -4.4274.

Although the value of R is constantly updated, only one value is added to RR.

RR = [];
for i=1:400
R = -abs(Ball_Distance -Ball_Target);
        RR(end+1) = R;　
end