complicated vectorization of for loop wich icludes if and referes back to last loop iteration results

I have heard, that it's possible to vectorize for loops even if the for loops are containing conditions and refer back to the results of the last loop iteration. Here a simple version of the code I am trying to voctorize.

Battery_storage = zeros(1, 365); % Value between 0 (empty) and 100 (full)

PV_power_available = round(rand(1,365)); % Random values of 0 and 1

% Look for every day, if the battery van be loaded or not:

for i =2:365

if Battery_storage(i-1)<80 && PV_power_available(i) == 1

% Load Battery by 20

Battery_storage(i) = Battery_storage(i-1) + 20;

else

% Deload Battery by 20

if Battery_storage(i-1) > 20

Battery_storage(i) = Battery_storage(i-1) - 20;

else

Battery_storage(i) = 0;

end

end

end

You would insanely help me, if you could provide me some feedback how to vectorize such a code. The "normal" code takes hours to run by using big for loops and many ifs. So I am trying to make it less time consuming.

Thanks ahead

Answer 1

[Jan]

Why do you assume, that a vectorization is faster? Neither loops nor IF-conditions are slow in modern Matlab versions.

Your code can be simplified:

for i = 2:365
    if Battery_storage(i-1)<80 && PV_power_available(i) % == 1
        % Load Battery by 20
        Battery_storage(i) = Battery_storage(i-1) + 20;
    elseif Battery_storage(i-1) > 20
        Battery_storage(i) = Battery_storage(i-1) - 20;
    % else  % 0 is the default already...
    %    Battery_storage(i) = 0;
    end
end

If PV_power_available is 0 or 1, you can omit the "==1".

This code cannot be vectorized.

Are you sure that this part is the bottleneck of your code?