Creating a random game of dice

This is what I have to do

disp('You are going to throw a dice and get the total for 5 tries')

de=[0 0 0 0 0]

for de(1,1)=ceil(rand*6);

disp(de(1))

end

And you do the same thing for each try

But it keeps giving me an error

Answer 1

[AJ von Alt]

A for loop needs an index variable and a set of values to loop through. Check out the documentation here. It has the form:

for index = values
   program statements
          :
end

I suspect you mean to do something like this:

disp('You are going to throw a dice and get the total for 5 tries')
de=[0 0 0 0 0]
for i = 1:6;

      de(i) = ??? % your code here

      disp( de(i) )
end

Pay careful attention to the de(i) syntax. We use de(i) instead of de(1), so that in the first run through of the loop we are working with de(1), in the second run through we get de(2) and so on all the way up to de(6).

Answer 2

[Image Analyst]

Why use a for loop when you can use randi():

numberOfThrows = 5;
throws = randi(6, numberOfThrows, 1)
sumOfThrows = sum(throws)

And you can put that into a loop over a million or so, if you want, then histogram the sums and plot it with bar().

% Monte Carlo Experiment.
numberOfThrows = 5;
histogram = zeros(numberOfThrows*6, 1);
numberOfExperiments = 100000;
for rolls = 1 : numberOfExperiments
  throws = randi(6, numberOfThrows, 1);
  sumOfThrows = sum(throws);
  histogram(sumOfThrows) = histogram(sumOfThrows) + 1;
end
bar(histogram);
grid on;
caption = sprintf('Results of %d Experiments of %d Throws Each', ...
  numberOfExperiments, numberOfThrows);
title(caption, 'FontSize', 13);
caption = sprintf('Sum of %d Throws', numberOfThrows);
xlabel(caption, 'FontSize', 20);
ylabel('Count', 'FontSize', 20);

[Riri]

Thank you but i'm not that advanced in matlab. I just started a week ago and i'm really having hard times understanding the fonction :(

[Image Analyst]

Wow. One line of code to do what you and AJ did in way more than that and you can't understand it? randi() is described in the help. The first argument says what the maximum integer is, which would be 6 in the case of dice. The next two numbers are the number of rows and columns. We just want 5 numbers for 5 dice thrown, so the second argument is 5 and the third one is 1. I hope you can follow that and start learning some very useful MATLAB functions. One call to randi and you can eliminate the for loop completely. The random number functions rand(), randi(), and randn() are three of the most commonly used functions and well worth learning .