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Re: srand versus srandom - srand with random() safe?

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"James H. Markowitz" <noone@nowhere.net> writes:
> On Mon, 17 Oct 2011 11:36:28 +0100, Ben Bacarisse wrote:
>> Arijit Das <arijit79@gmail.com> writes:
>> 
>>> Can srand() be safely used for seeding subsequent random() calls?
>>>
>>> And vice versa? Can srandom() be used for seeding subsequent rand()
>>> calls?
>> 
>> Because seeding an RNG should be a once-off action, and the seed is
>> essentially arbitrary, it probably doesn't matter much.  But one of the
>> most common errors that people make is to seed an RNG too often in an
>> attempt to "mix things up" more.
>
> 	How do you determine "too often", and why would that be an error? 
> I understand it would perhaps be a waste of computational resources, but 
> not an error. Leaving the "too often" admonition aside, and assuming the 
> use of genuine random seeds, is seeding a PRNG regularly (unpredictably, 
> if possible) not a good idea? 

Unless you have a specific need to repeat a known sequence, a PRNG
should be seeded exactly once during the execution of the program,
before any calls to the generator.

It's rand()'s job to generate pseudo-random numbers.  Re-seeding it just
interferes with it.

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"

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srand versus srandom - srand with random() safe? Arijit Das <arijit79@gmail.com> - 2011-10-17 01:15 -0700
  Re: srand versus srandom - srand with random() safe? "Joachim Schmitz" <nospam.jojo@schmitz-digital.de> - 2011-10-17 11:12 +0200
  Re: srand versus srandom - srand with random() safe? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-10-17 11:36 +0100
    Re: srand versus srandom - srand with random() safe? "James H. Markowitz" <noone@nowhere.net> - 2011-10-17 17:01 +0000
      Re: srand versus srandom - srand with random() safe? Keith Thompson <kst-u@mib.org> - 2011-10-17 12:19 -0700
      Re: srand versus srandom - srand with random() safe? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-10-17 20:38 +0100
        Re: srand versus srandom - srand with random() safe? Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-10-18 01:08 -0700
  Re: srand versus srandom - srand with random() safe? Nobody <nobody@nowhere.com> - 2011-10-17 13:37 +0100
    Re: srand versus srandom - srand with random() safe? "Morris Keesan" <mkeesan@post.harvard.edu> - 2011-10-17 12:36 -0400
  Re: srand versus srandom - srand with random() safe? gordonb.ep2p2@burditt.org (Gordon Burditt) - 2011-10-17 12:55 -0500
    Re: srand versus srandom - srand with random() safe? Keith Thompson <kst-u@mib.org> - 2011-10-17 12:24 -0700
      Re: srand versus srandom - srand with random() safe? gordonb.p3quo@burditt.org (Gordon Burditt) - 2011-10-17 17:19 -0500
        Re: srand versus srandom - srand with random() safe? James Kuyper <jameskuyper@verizon.net> - 2011-10-17 19:45 -0400
          Re: srand versus srandom - srand with random() safe? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-10-18 02:45 +0100
          Re: srand versus srandom - srand with random() safe? rudolf <r.thered@gmail.com> - 2011-10-18 00:11 -0700
            Re: srand versus srandom - srand with random() safe? Keith Thompson <kst-u@mib.org> - 2011-10-18 00:25 -0700

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