How to Shorten running time

Hi, I am new to matlab and I am given an assignment.

I am supposed to find the most suitable feed rate (Ft) that produces the highest amount of biomass, lowest ethanol and uses the least glucose.

How do I shorten the running time for this code? It has been running for quite a while. If there is anything wrong with it, please let me know. I read that maybe parfor loops can shorten running time but I have not learnt them in class and I am unsure of how to use it. Is it applicable in this code?

%given variables
Agitator_speed=803;
Aeration_rate=1;
Fermenter_volume=618;
Fermenter_initial_glucose_concentration=32;
Fermentation_temperature=39;
Feed_glucose_concentration=111;
Batch_time=1:60;
Total_biomass_produced=5606.3595;
Total_ethanol_produced=0.0046638;
Total_glucose_used=4599.3704;
%feed rate
a=1; b=1;
D1=a*ones(1,60)';
D2=b*[60,120]'/60;
Ft=[D1;D2];
best_batch_time=100;
best_ethanol_produced=100;
best_glucose_used=100;
best_biomass_produced=1;
while react_vol<Fermenter_volume
   %calculate the values of each variable
   for i=1:100       
       x=biomass_conc(:,i);
       y=react_vol(:,i);best_ethanol_produced;
       q=ethanol_conc(:,i);
       m=gluc_conc(:,i);
       total_biomass_produced=x*y;
       total_ethanol_produced=q*y;
       total_glucose_used=m*y;
   end
   %checking if the current Ft is the optimum (comparing variables)
       if Batch_time<=best_batch_time
            best_batch_time=Batch_time;
           
            if total_ethanol_produced<=best_ethanol_produced
                best_ethanol_produced=total_ethanol_produced;
               
                if total_glucose_used<=best_glucose_used
                    best_glucose_used=total_glucose_used;
                   
                    if total_biomass_produced>=best_biomass_produced
                        best_biomass_produced=total_biomass_produced;
                    end
                end
            end
              best_feed_rate=Ft;
       end
   a=a+1;b=b+1;
end
        fprintf('the batch time is %d\n',best_batch_time)
        fprintf('the total ethanol produced is %d\n',best_ethanol_produced)
        fprintf('the total glucose used is %d\n',best_glucose_used)
        fprintf('the total biomass produced is %d\n',best_biomass_produced)

[DGM]

Right off the bat, the code doesn't even run as given, so either something is missing or it's thrown an error. You're referencing arrays that don't exist:

       x=biomass_conc(:,i);
       y=react_vol(:,i);best_ethanol_produced;
       q=ethanol_conc(:,i);
       m=gluc_conc(:,i);

I can't guess what size they're supposed to be.

Furthermore, that second line is two statements:

y=react_vol(:,i); % this statement assigns something to a variable
best_ethanol_produced; % this statement does nothing

This logical test doesn't look like it's going to work either

    if Batch_time<=best_batch_time

You're comparing a scalar and a vector; you'll wind up with a logical vector instead of a single logical value

[sean loh]

There is a protected file that contains the values to this script.

what do you mean by comparing a scalar and a vector? could you elaborate.

[Walter Roberson]

1:10 < 7

ans = 1×10 logical array
   1   1   1   1   1   1   0   0   0   0

Left side of the < is a vector (like Batch_time is a vector) and right side is a scalar (like best_batch_time is). The result, as you can see, as a logical vector that indicates whether each individual comparison was true.

When you have a vector test like that in an if statement, the if is considered true only if every value being tested is non-zero. Equivalent, that is to say, to

all(1:10 < 7)

ans = logical
   0

which is false if there is even one entry which is 0 (false)

   for i=1:100       
       x=biomass_conc(:,i);
       y=react_vol(:,i);best_ethanol_produced;
       q=ethanol_conc(:,i);
       m=gluc_conc(:,i);
       total_biomass_produced=x*y;
       total_ethanol_produced=q*y;
       total_glucose_used=m*y;
   end

Notice that you overwrite total_biomass_produced and total_ethonal_produced and total_glucose_produced every iteration of for i