monte carlo simulation in matlab two dices roll

if 2 dices were thrown & there top value were added ,what is the probability of getting a sum of 7 ?

[John BG]

Hi Isuru

this is John BG <mailto:[e-mail] [e-mail]>

One thing is to olve a problem with the Montecarlo approach: plugging in a large enough number of random inputs that give a clear enough shape of the solution.

An example of the Montecarlo approach to predict data is:

https://uk.mathworks.com/help/finance/examples/pricing-american-basket-options-by-monte-carlo-simulation-1.html

The other thing, that may be related, but still do not understand how you want it linked to the Montercarlo approach, is to calculate the probability of 2 simultaneous dice sum equal 7.

Would you please be so kind to clarify a bit by adding some MATLAB code that you may have already written?

appreciating time and attention, awaiting answer

[John D'Errico]

This is just a question about probability, not about MATLAB at all. So if you want some help on it, you need to show what you are doing in MATLAB on it. Otherwise, this becomes just a doit4me on your homework.

[isuru senevirathne]

for i=1:10
throws1 = randi(6, 1);
throws2=randi(6,1);

    if true
      % code
    end
  sum=throws1+throws2
         if sum ==7

   sprintf('%s','sum is 7')

         else
      sprintf('false ')

         end

end
-----------

i want to count the amount , how many times these two dices (sum) is equal 7 pls modified according to Montecarlo approach

[Jeff Miller]

to count the number of 7's, use a counter variable, e.g., Ctr. Set it to zero before you start the loop, and then add one to it each time your sum equals 7. When the loop finishes, the value in Ctr will be the number of 7's that were found.

[Image Analyst]

isuru, here's a tip to format your code correctly. In MATLAB type control-a control-i to properly indent your code. Then copy it and paste it here. Highlight the code and then click the {}Code button. See this link

And note how Jan's properly formatted answer below does not use sum as the name of a variable so as to not override the built-in sum function.

Answer 1

[Jan]

n        = 10;               % Number or trials
throw    = randi(6, n, 2);   % Value of throws, 2 dice
SumThrow = sum(throw, 2);    % Sum of both dice
Match    = (SumThrow == 7);  % Logical array: 1 if sum of values is 7
count    = sum(Match);       % Number of matching throws

Or with modifications of your code:

count = 0;
for i=1:10
  throws1  = randi(6, 1);
  throws2  = randi(6, 1);
  sumThrow = throws1 + throws2;   % Do not use "sum" as name of a variable
  if sumThrow == 7
    fprintf('sum is 7\n')
    count = count + 1;
  else
    fprintf('false\n')
  end
end
fprintf('Number of throws with sum=7: %d\n', count);

Answer 2

[Md Jilani]

Hello sir, Good Day. How can I get probabilty from here ?

[Jan]

Please do not post new questions in the section for answers. Prefer to open your own thread. Thanks.

My code counts the number of 7's in the variable count for n throws. Then the probability is approximately n / count.

You can determine the probability in a constructive way also:

nAll = 0;
n7   = 0;
for throw1 = 1:6
    for throw2 = 1:6
        nAll = nAll + 1;
        if throw1 + throw2 == 7
            n7 = n7 + 1;
        end
    end
end

n7 / nAll

Of course you can do this manually also, because the calculations are very easy: There are 36 possible throws with 2 dice. You get a sum of 7 for 1+6, 2+5, 3+4, 4+3, 5+2 and 6+1: 6 possibilities.