Array elements are recalculated every iteration

I am trying to calculate Tprod using waklkin temperature calculated by an other shoftware using the code below, which recalculates all elements of the Tprod array in every iteration as shown below.

How can I modify my code to calculate only one Tprod(i,j) at each time step using a single Twalkin(i,j), instead of recalculating the entire Tprod array every iteration?

nRows = ceil(endTime / ep.timestep); %Query timestep after mlep initialization
%logTable
logTable = table('Size',[0, 1 + ep.nOut],...
    'VariableTypes',repmat({'double'},1,1 + ep.nOut),...
    'VariableNames',[{'Time'}; ep.outputSigName]);
iLog = 1;

% Start the co-simulation process and communication. 
ep.start

%Data
t = 0;  h=10 ; s= 1; m=100 ; cp= 3230; Tprodi= 30; 

% The simulation loop  

while t < endTime
    % Specify inputs
    u = [200]; % Initial value to be sent to EnergyPlus
    
    % Send inputs & get outputs from EnergyPlus
    y = ep.step(u); 
    % Obtain elapsed simulation time 
    t = ep.time; %[s]
    % Walkin Temperature
    Twalkin= table2array(logTable(:,2:2))
     Q=m*cp*(Tprod - Twalkin);
   
    % Product Temperature
    Tprod = Twalkin + (Tprodi - Twalkin)*exp(-t*(h*s)/(m*cp))
  
    logTable(iLog, :) = num2cell([t y(:)']);
    iLog = iLog + 1; 
 
end

Twalkin =
  -20.1041
Tprod =
   29.9070
_________________
Twalkin =
  -20.1041
  -19.2153
Tprod =
   29.8142
   29.8175
_________________
Twalkin =
  -20.1041
  -19.2153
  -18.6658
Tprod =
   29.7216
   29.7265
   29.7296
_________________
Twalkin =
  -20.1041
  -19.2153
  -18.6658
  -18.2641
Tprod =
   29.6291
   29.6357
   29.6397
   29.6427

Answer 1

[VBBV]

This is one approach, where you can initialize a variable k and iterate along the time step

nRows = ceil(endTime / ep.timestep); %Query timestep after mlep initialization
%logTable
logTable = table('Size',[0, 1 + ep.nOut],...
    'VariableTypes',repmat({'double'},1,1 + ep.nOut),...
    'VariableNames',[{'Time'}; ep.outputSigName]);
iLog = 1;

% Start the co-simulation process and communication. 
ep.start

%Data
t = 0;  h=10 ; s= 1; m=100 ; cp= 3230; Tprodi= 30; 

% The simulation loop  
k = 1;
while t < endTime
    % Specify inputs
    u = [200]; % Initial value to be sent to EnergyPlus
    
    % Send inputs & get outputs from EnergyPlus
    y = ep.step(u); 
    % Obtain elapsed simulation time 
    t = ep.time; %[s]
    % Walkin Temperature
    Twalkin= table2array(logTable(:,2:2))
   
    % Product Temperature
    Tprod(iLog,k) = Twalkin(iLog,2) + (Tprodi - Twalkin(iLog,2))*exp(-t*(h*s)/(m*cp))
  
    logTable(iLog, :) = num2cell([t y(:)']);
    iLog = iLog + 1; 
    k = k+1;
 
end

[Zakaria OUAOUJA]

Thank you for your answer.

I have tried to ran the scripte with the modification you suggested and display the following error.

Index in position 2 exceeds array

bounds (must not exceed 1).

Error in mlepMatlab_example (line74)

Tprod(iLog,k) = Twalkin(iLog,2) + (Tprodi - Twalkin(iLog,2))*exp(-t*(h*s)/(m*cp));

[VBBV]

logTable = num2cell([t*ones(length(y(:)),1) y(:)]);

Change also this line as above