Matlab gets stuck - No error message

Dear All,

I am stuck with a real problem. I have written a script (please see blow the summary) that works well, but sometimes for no apparent reason it gets stuck. I firmly say it is not an endless loop.

I would be very thankful if you provide me with any suggestions, as I tried many and it didn't work. The main reason that I can think of is that the problem could be associated with the RAMs! Especially when the number of iterations within the while loops become large. If this is the case, is there a way to keep refreshing the memory?

Kindly note that the machine I am using is QuadCore, Intel Xeon® @ 2.4 GHz, 64 GB Rams

Since I already started the post; does anyone know a way that makes this simulation faster? (any hints, or toolbox that does the trick)

Thanks Experts, I really appreciate your help.

%script - kindly note that afterwards, I export the results to excel
%defining No of Simulations & the steps
ii = 10000000;
Min = 100;
Max = 110;
Steps = 1;
Observations = ((Max - Min)/Steps)+1;
PriceVector = Min:Steps:Max;
%Defining Parameters
...
...
StartingTime=0;
StartingDay=0;
EndingDay=20;
...
...
%Creating Matrices for speeding up the process
frequency = zeros(ii,Observations); 
Count = zeros (ii,Observations);
DayX = zeros(1,Observations);
DayY = zeros(1,Observations);
SurV = zeros(1,Observations);
ONX = zeros(1,Observations);
PriceVec = zeros(1,Observations);
%Initiating the progress bar
multiWaitbar('Main for loop',0,'Color', 'b'); %progress bar of #Ben Tordoff.
multiWaitbar('Sub for loop',0, 'Color', 'g');

for j=1:Observations 
        values =  zeros(1,ii);%to speed up the process
        Incremental=PriceVector(j);%this gets the next incremental value
        for i=1:ii;
            StockPrice=Incremental;
            Days=StartingDay; %start day
            Hours=StartingTime;
            knockout = 0; %This variable will terminate the while loop when false
               while knockout == 0
                   %some calculations
                   knockoutNew = 0;
                   while (knockout == 0 && knockout2 == 0)
                       %some calculations
                       Hours = Hours + SS %SS is the sampling interval
                       if true %first condition
                           value = 0;
                           knockout = 1;

                         elseif true %sub condition
                          knockout2 = 1;
                         end
                     end

                     if true %first condition - Breaking the first while loop since the condition is met in the sub loop
                         break
                     end

                     if Hours < 1
                         %some calculations
                          if true %second condition
                              value = 0;
                              knockout = 2;
                          end
                     else
                         if Days==EndingDay; %third condition 
                                  value = 5; 
                                  knockout=3;
                         else
                             %some calculations
                              if true %fourth condition
                              value = 0;
                              knockout = 4;
                              else
                              Days=Days+1; %this ensure the termination of the loop
                              Hours = 0;
                              end
                         end
                     end
                 end
              values(i) = value; %gets the values of the knockout i.e, either zero or 5 
              frequency(i) = knockout;
              %progress of the sub for loop
              multiWaitbar('Sub for loop',i/ii);
          end
          Kvalue=%somecalulations; 
          kboV(j)=KBO; 
          %collecting the count of each case of each price element
          DaytimeKO(j)=sum(histc(frequency,1));
          DayJumpKO(j)=sum(histc(frequency,2));
          Survival(j)=sum(histc(frequency,3));
          ONightKO(j)=sum(histc(frequency,4));
          PriceVec(j) = Incremental;
      %progress of the main for loop    
      multiWaitbar('Main for loop',j/TotalProcess); 
  end

Answer 1

[dpb]

I firmly say it likely (given the pseudo-code if...end conditional blocks above) IS occasionally finding a set of conditions that are an infinite loop.

Memory refresh is a hardware-implemented feature of the machine; that or similar things is not in any way at all a feasible/likely cause for your problem, it is almost certainly a logic problem for a certain set of data inputs.

There's insufficient detail to tell for certain but I'd suspect if one had the overall actual code one could vectorize the loop and logic almost if not entirely from the way it appears structured overall.

[AND]

Thanks #dpb for the answer,

I would relax if it is a coding issue. The only way that I get into an infinite loop is through the 2 while-loops I have, this if I am not wrong.

I tried the main-while loop, and it is not forsure causing any problem. While I am writing this comment, I am actually running the code, and looking if there is a problem with the sub-while loop.

Since this doesn't occur frequently, I have to wait and see how it goes. To debug the problem, I am printing a counter, but this slows the process; do you know a faster method?

I apologize for not stating the sub condition of the inner loop as it is fundamental, it goes:

else if Hours > 1 %this makes sure there is an end to this loop, as Hours is increasing in every loop

The following ensures the termination of the main-while loop:

Days=Days+1; % it starts at 0, once it becomes 20, it terminates

I thought it is a memory issue, because Matlab blocks the memory for creating the matrices.

I shall keep you updated anyways,

Thanks again & best if regards//

[dpb]

I thought it is a memory issue, because Matlab blocks the memory for creating the matrices.

??? What is this supposed to mean? If Matlab has an out-of-memory problem it'll abort and tell you so.

If there's something in there that's not pre-allocated and you're doing allocation on the fly that haven't caught that'll definitely bog it down with increasing sizes.

The mlint and code editor ought to be able to spot that if so altho there are some ways that are harder to find than others...

Again, I'd look real hard at vectorizing the whole thing--looks to me like you should be able to get rid of the loop structure almost entirely. Perhaps you'll need to restructure slightly to eliminate all but it just looks to me like reorganizing is the first place to look.

It again needs more of the pertinent details of the code an perhaps less of the not-so-much to really get anywhere for anybody here in that regard...

[AND]

The problem only occurs, when I run another process(s) without restarting Matlab. Of course it is not an out-of-memory problem, otherwise I would get the message.

I tried the mlint function but it retrieved no errors or recommendations.

All what I can do to solve the problem now is to restart Matlab after every 1 or 2 simulation processes.

Anyways #dpb, many thanks for your contributions; I do appreciate it.

Best of Regards//

[dpb]

The problem only occurs, when I run another process(s) without restarting Matlab....

So, the problem likely isn't Matlab at all, iow.

I still think you should look at restructuring your code and vectorizing it extensively and would find marked improvement in performance if did so...

ADDENDUM:

I pasted your code in the editor w/ the intent of trying to actually look at the above but the missing conditionals even w/ the incomplete description you added make doing anything useful impossible as far as seeing how vectorization might solve your problems. :(