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MATLAB question-factorial

  1. Oct 22, 2011 #1
    So I am trying to plot the birthday problem.

    Number of people vs chance not to have the same birthday.

    I know the analytical form

    [itex] P(n)={\Large\frac{365\cdot 364\cdot 363...(365-n+1)}{365^{n}}}[/itex]

    problem is, matlab is giving me this, when I try to put that into code.

    [PLAIN]http://pokit.org/get/e8cbb0974a4b30d349d554c27ab0f537.jpg [Broken]

    And thats only trying to realise the top part of the fraction.

    I am trying to get this result.


    Source wikipedia.

    Thank you.
    Last edited by a moderator: May 5, 2017
  2. jcsd
  3. Oct 22, 2011 #2

    Dr Transport

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    looks like you are not dividing by 365 to the nth power
  4. Oct 23, 2011 #3
    Still he is giving me infinity. I think he calculates factorial first, then to the nth, then divides that and still gets infinity
  5. Oct 23, 2011 #4


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    Unfortunately, MATLAB has maxima on both integers and floating point numbers:

    I believe that both are exceeded by the calculations that you're trying to make in the numerator and denominator.

    However, I believe that you can do this recursively (i.e. start with n=0, and use this result to generate n=1, use that result to generate n=2, etc.)
  6. Oct 23, 2011 #5
    My hero <3 Thank you!
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