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Topic: Random numbers
Replies: 64   Last Post: Dec 24, 2007 1:04 PM

 Messages: [ Previous | Next ]
 quasi Posts: 12,067 Registered: 7/15/05
Re: Random numbers
Posted: Dec 22, 2007 1:35 PM

On Sat, 22 Dec 2007 10:32:37 -0800 (PST), vr <simple.popeye@gmail.com>
wrote:

>On Dec 22, 11:16 pm, quasi <qu...@null.set> wrote:
>> On Fri, 21 Dec 2007 10:57:00 -0800 (PST), simple.pop...@gmail.com
>> wrote:
>>
>>
>>
>>
>>

>> >On Dec 21, 11:37 pm, bill <b92...@yahoo.com> wrote:
>> >> On Dec 21, 3:16 am, John <iamach...@gmail.com> wrote:
>>
>> >> > Given a function that returns a random number between 1-5, write one
>> >> > that returns a random number between 1-7 for the case when it should
>> >> > be integer and for the case it can be real.

>>
>> >> Let S be the function that generates a RN between 1 and 5.  Then
>>
>> >> T =  S_1 + S_2 + ... + S_7
>>
>> >> For the reals , RN_7 = T/7
>>
>> >May be this should fix it:
>>
>> >For the reals , RN_7 = 1 + (T-7)*3/14
>>
>> Yes, that fixes the range.
>>
>> But it's still biased (that is, not a unform distribution).
>>
>> quasi- Hide quoted text -
>>
>> - Show quoted text -

>
>Hmm. Let me simplify it:
>
>RN_7 = T*3/14 - 0.5
>
>If you look at T*3/14, it just scales the sum of random numbers
>uniformly using a constant multiplier. Did I miss to notice any non-
>uniformity here?

Yes, T is not uniformly distributed in its range.

quasi

Date Subject Author
12/21/07 Champ
12/21/07 quasi
12/21/07 quasi
12/21/07 Phil Carmody
12/21/07 quasi
12/21/07 quasi
12/21/07 Phil Carmody
12/21/07 quasi
12/21/07 Phil Carmody
12/21/07 Phil Carmody
12/21/07 quasi
12/21/07 quasi
12/21/07 Phil Carmody
12/21/07 quasi
12/21/07 Phil Carmody
12/21/07 Phil Carmody
12/21/07 quasi
12/21/07 Phil Carmody
12/21/07 quasi
12/21/07 Marshall
12/21/07 Phil Carmody
12/21/07 quasi
12/21/07 Phil Carmody
12/21/07 Marshall
12/21/07 briggs@encompasserve.org
12/21/07 William Elliot
12/21/07 quasi
12/22/07 William Elliot
12/21/07 Pubkeybreaker
12/21/07 b92057@yahoo.com
12/22/07 quasi
12/21/07 simple.popeye@gmail.com
12/21/07 simple.popeye@gmail.com
12/22/07 quasi
12/22/07 Gib Bogle
12/22/07 quasi
12/21/07 Marshall
12/22/07 simple.popeye@gmail.com
12/22/07 quasi
12/22/07 simple.popeye@gmail.com
12/22/07 quasi
12/22/07 quasi
12/22/07 quasi
12/22/07 simple.popeye@gmail.com
12/22/07 quasi
12/23/07 simple.popeye@gmail.com
12/23/07 simple.popeye@gmail.com
12/23/07 simple.popeye@gmail.com
12/23/07 simple.popeye@gmail.com
12/23/07 simple.popeye@gmail.com
12/22/07 simple.popeye@gmail.com
12/22/07 Herman Rubin
12/22/07 b92057@yahoo.com
12/22/07 quasi
12/23/07 b92057@yahoo.com
12/23/07 quasi
12/23/07 b92057@yahoo.com
12/24/07 quasi
12/24/07 quasi