The main change I made was to update the tally(k) value inside the for loop instead of assigning it at the end. This way, the tally array is populated with the probability values for each sample size.
disp('Welcome to the Birtday Paradox');
ready = false;
while ~ ready
% User inputs and defining variables
birthday_repeats = input('select the number of birthday repeats from 10-500:');
if birthday_repeats > 500 || birthday_repeats < 10 || isempty(birthday_repeats) || round(birthday_repeats) ~= birthday_repeats || isnan(birthday_repeats)
disp('error')
continue
end
sample_size = input('Select the sample size from 2-365: ');
if sample_size > 365 || sample_size < 2|| isempty(sample_size) || round(sample_size) ~= sample_size || isnan(sample_size)
disp('error')
continue
end
N = 1000;
days = randi(365,1,365);
tally = zeros(1,sample_size);
% simulation run
for k = 2:sample_size
match = 0;
for j = 1:birthday_repeats % desired number of trials
birthdays = randi(365,1,k);
if test(birthdays)
match = match + 1;
end
end
tally(k) = match/birthday_repeats;
end
% plotting graphs
domain = 2:sample_size;
figure(1)
plot(domain,tally(2:end))
xlabel('Number of people Chosen')
title('Birthday Paradox simulation')
ylabel('Probability')
fprintf('the probability array is:\n');
disp(tally(2:end))
break
end
function out = test(data)
out = false;
n = length(data);
for k = 1:n
for i = k+1:n
if data(k) == data(i)
out = true;
return
end
end
end
end
