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Date: Mon, 12 Jan 2009 20:56:11 -0800 To: boost-users@lists.boost.org From: marshall@idio.com Subject: Re: [Boost-users] Random Numbers using Boost.
At 7:21 PM -0600 1/12/09, Atul Kulkarni wrote:
Hi All,
I am using boost::random for generating random numbers I am using the default quick start code given up on the web page. I want to generate random numbers between range 1 - n so that they do not repeat themselves for at least n numbers.
I'm not sure if shuffling is the best approach as described on wiki as it suggests an indirect method using random numbers to shuffle a set of unique entries. The polynomial approach is more direct and may be worth considering. You want some kind of pseudorandom generator, something based on a polynomial would be worth considering. Essentially you want a counter modulo n and a look up table ( presumably with no repeating entries which you could generate from the shuffing approach cited earlier). Think about something like your output sequence g generated from g(n+1)=(F(g(n))%n where you need to constrain F so that the period isn't reduced. http://www.google.com/search?hl=en&q=pseudorandom++polynomial+site%3Awikipedia.org This is just a state machine with a concise transition rule.
1. Is it possible using boost::random? 2. If it is possible what do I need to do except the below code.
== boost::mt19937 rng1; boost::uniform_int<> six1(1,30); boost::variate_generator>>boost::uniform_int<>> die1(rng1, six1); for(int i=0; i < 29; i++) { cout<>> } ==
This will not satisfy your preconditions, except by accident. A random number generator will, at random times, output the same number twice in a series.
If you want to choose numbers w/o repeating, that's more akin to shuffling the cards in a deck - and there are lots of online resources on how to do that (alternately, you can look in Knuth). See for one.
-- -- Marshall
Marshall Clow Idio Software
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