Simulating 10 biased coin flips 100 times

n = 10; %amount of flips done 1 million times
arr = zeros(n); %array to store heads in n flips
toss = (U < 0.6388888888888); %biased coin toss probability

while j < 10 %Repeating the 10 coin flips 100 times
  heads = 0; %Reset heads counter
  for i = 1:n %The 10 coin flips
  U = rand(0,1); %Rng
      if U < 0.6388888888888 %Head/tail counter
      heads = heads + 1; %Amount of heads /10 tosses total counter
      end
  end
arr(heads) = arr(heads) + 1; %accessing point in array and adding one tick
j = j + 1; %ticker for while loop
end

histogram(arr) %graphing

As the title says, I am trying to code 10 coin tosses 100 times. And I am also trying to graph it. However the program enevr runs or graphs correctly. Rather general question but I can't find the error? I think it's the "arr(heads) = arr(heads) + 1" because I've reread it a ton but I'm stuck.

Answer 1

[Voss]

rand(0,1) returns a 0-by-1 array.

rand() returns a (uniformly distributed) random number between 0 and 1.

See other changes below:

n = 10; %amount of flips done 1 million times
% arr = zeros(n); %array to store heads in n flips
arr = zeros(1,100);
% toss = (U < 0.6388888888888); %biased coin toss probability

j = 1;
% while j < 10 %Repeating the 10 coin flips 100 times
while j <= 100 %Repeating the 10 coin flips 100 times
    heads = 0; %Reset heads counter
    for i = 1:n %The 10 coin flips
%         U = rand(0,1); %Rng
        U = rand();
        if U < 0.6388888888888 %Head/tail counter
            heads = heads + 1; %Amount of heads /10 tosses total counter
        end
    end
%     arr(heads) = arr(heads) + 1; %accessing point in array and adding one tick
    arr(j) = heads;
    j = j + 1; %ticker for while loop
end
histogram(arr) %graphing
xlabel(sprintf('# of heads in %d coin flips',n))