I have trouble with me homework.
so the problem is this: i have n fair dices with 6 sides that roll all together and i need to calculate the probability of sum of dices side.
i need to write script when:
function prob = sumDicePDF(n,k) input: 1. number of dices(n >= 1) 2. k - integer number from n to 6n output: probability
example: sumDicePDF(3,4) ans = 0.0139 sumDicePDF(8,20) ans = 0.0218
i need to use equalition: probability = sigma[1:6](P(sum(n-1) = k - i) * 1/6
and i forbiden to use recursion so my script run time must be near n^2
i understood the problem but i cant find a way to biuld the loop for counting probability so my answer be prob=(1/6)^n*sumOfCounting;
so my quastion is how to make loop to find sumOfCounting.
vec = ones(1,n - 1); sumOfCounting = 0; for i = 1:6 for j = 1:length(vec) vec(j) = i; sumOfvalue = sum(vec); if k - sumOfvalue < 7 && k - sumOfvalue > 0 for m = 1:length(vec) sumOfCounting = sumOfCounting + length(vec) + 1 - m; end end end end
but it not counting all options so where is the problem?
thank and best wishes.
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Nice try, but why not just use the sum() function - that's what it's there for:
% Roll the dice "numberOfRolls" times numberOfRolls = 200; % Number of times you roll all 6 dice. n = 10; % Number of dice. maxFaceValue = 6; rolls = randi(maxFaceValue, n, numberOfRolls)
% Sum up dice values for each roll. columnSums = sum(rolls, 1) % Find out how many times each sum occurred. edges = min(columnSums):max(columnSums) counts = histc(columnSums, edges) % Normalize grandTotalSum = sum(counts(:)) normalizedCountSums = counts / grandTotalSum bar(edges, normalizedCountSums, 'BarWidth', 1); grid on; % Enlarge figure to full screen. set(gcf, 'units','normalized','outerposition',[0 0 1 1]); % Give a name to the title bar. set(gcf,'name','Demo by ImageAnalyst','numbertitle','off') title('Frequency of Roll Sums', 'FontSize', 40);