Creating a random game of dice

Question

Riri 2014-1-20

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/113048-creating-a-random-game-of-dice

评论： Image Analyst 2014-1-21

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

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

AJ von Alt 2014-1-20

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/113048-creating-a-random-game-of-dice#answer_121557

编辑：AJ von Alt 2014-1-20

在 MATLAB Online 中打开

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).

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

Answer 2

Image Analyst 2014-1-20

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/113048-creating-a-random-game-of-dice#answer_121559

编辑：Image Analyst 2014-1-20

在 MATLAB Online 中打开

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);

2 个评论
显示无隐藏无

Riri 2014-1-20

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 2014-1-21

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 .

请先登录，再进行评论。