MATLAB: Index exceeds matrix dimensions

random

clear
clc
count_eight=0;
clear
clc
count_eight=0;
RandStream.setDefaultStream = (RandStream('mt19937ar','seed',sum(100*clock)));
roll=input('Enter number of rolls \n');
for rolling = 1:roll
      dice1 = randi(6);
      dice2 = randi(6);
end
if dice1+dice2==8
      count_eight=count_eight+1;
  end
fprintf('Percentage of times an 8 appeared %.1f ',count_eight(roll*100));
display('End of Program')
roll=input('Enter number of rolls \n');
for rolling = 1:roll
      dice1 = randi(6);
      dice2 = randi(6);
end
if dice1+dice2==8
      count_eight=count_eight+1;
  end
fprintf('Percentage of times an 8 appeared %.1f ',count_eight(roll*100));
display('End of Program')
ERROR MESSAGE:
??? Index exceeds matrix dimensions.
Error in ==> Homework10 at 51
fprintf('Percentage of times an 8 appeared
%.1f ',count_eight(roll*100));

Best Answer

Well at least you made a good attempt at it. but count_eight is a scalar while you try to print it out as an array in your fprintf. Try it this way:
clear;
clc;
count_eight=0;
RandStream.setDefaultStream = (RandStream('mt19937ar','seed',sum(100*clock)));
response = inputdlg('Enter number of rolls \n');
roll = str2double(response{1});
for rolling = 1:roll
    dice1 = randi(6);
    dice2 = randi(6);
  if dice1+dice2==8
    count_eight=count_eight+1;
  end
end
message = sprintf('8 appeared %d times in %d rolls = %.2f%%', ...
  count_eight, roll, count_eight/roll*100);
uiwait(msgbox(message));
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