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MathGroup Archive 1995

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Re: Random[BinomialDistribution[..]] wrong ?

  • To: mathgroup at christensen.cybernetics.net
  • Subject: [mg1071] Re: Random[BinomialDistribution[..]] wrong ?
  • From: rubin at msu.edu (Paul A. Rubin)
  • Date: Fri, 12 May 1995 17:10:59 -0400
  • Organization: Michigan State University

In article <3olugl$ql4 at news0.cybernetics.net>,
   bzbkowal at ZIB-Berlin.DE (Axel Kowald) wrote:
->I'm using Mathematica 2.2 on a Macintosh and I got a problem generating 
binomially
->distributed random numbers.
->
->I have:
->
->Needs["Statistics`DiscreteDistributions`"]
->SeedRandom[17]
->Table[Random[BinomialDistribution[10^6,0.01]],{5}]
->Out-> {998486, 998486, 998486, 998486, 998486}
->
->Not only that the random numbers are all the same, most importantly they 
are in a 
->completely wrong range. One should get something around 10000 !
->The problem seems to be 10^6, if I use something smaller, like 10000, 
everything works
->fine. Furthermore the problem seems to be in the Random[] function since
->PDF[BinomialDistribution[10^6,0.01],n] works okay (but takes a long 
time).
->
->Any comments, hints, solutions ?

I pasted your input statements into version 2.2.2 for Windows and got 
something different (and a lot more reasonable):

  {9996, 9954, 9854, 10107, 9837}

If another Mac user can reproduce the problem, then I would suspect it to 
be a bug in the Mac kernel.

Paul


**************************************************************************
* Paul A. Rubin                                  Phone: (517) 432-3509   *
* Department of Management                       Fax:   (517) 432-1111   *
* Eli Broad Graduate School of Management        Net:   RUBIN at MSU.EDU    *
* Michigan State University                                              *
* East Lansing, MI  48824-1122  (USA)                                    *
**************************************************************************
Mathematicians are like Frenchmen:  whenever you say something to them,
they translate it into their own language, and at once it is something
entirely different.                                    J. W. v. GOETHE


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