From owner-sc22wg5@open-std.org Thu Oct 22 20:00:52 2009 Return-Path: X-Original-To: sc22wg5-dom8 Delivered-To: sc22wg5-dom8@www2.open-std.org Received: by www2.open-std.org (Postfix, from userid 521) id 9FACEC76BC4; Thu, 22 Oct 2009 20:00:52 +0200 (CET DST) X-Original-To: sc22wg5@open-std.org Delivered-To: sc22wg5@open-std.org Received: from ironport1.lbl.gov (ironport1.lbl.gov [128.3.41.47]) by www2.open-std.org (Postfix) with ESMTP id D7FAFC178E4 for ; Thu, 22 Oct 2009 20:00:50 +0200 (CET DST) X-Ironport-SBRS: None X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: ArEEALs64EqAAwU8/2dsb2JhbACBUstYCY8qAoJTgWoE X-IronPort-AV: E=Sophos;i="4.44,606,1249282800"; d="scan'208";a="124508780" Received: from angilas.lbl.gov (HELO angilas.localnet) ([128.3.5.60]) by ironport1.lbl.gov with ESMTP/TLS/DHE-RSA-AES256-SHA; 22 Oct 2009 11:00:49 -0700 From: Aleksandar Donev Organization: LBL To: SC22WG5 Subject: Re: (j3.2006) (SC22WG5.4115) Parallel random numbers Date: Thu, 22 Oct 2009 11:00:49 -0700 User-Agent: KMail/1.11.2 (Linux/2.6.28-15-generic; KDE/4.2.2; x86_64; ; ) References: <20091020111544.C0F5CC178E3@www2.open-std.org> <20091022160201.90187C76BB7@www2.open-std.org> <20091022172236.755B9C76BB7@www2.open-std.org> In-Reply-To: <20091022172236.755B9C76BB7@www2.open-std.org> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200910221100.49209.adonev@lbl.gov> Sender: owner-sc22wg5@open-std.org Precedence: bulk On Thursday 22 October 2009, Bill Long wrote: > You want the "same default seed", right? Each image should be able > to independently change its own seed. Do we say anything now about default seed? What I meant was that if each image sets the seed identically and then calls random_number the same number of times, they all get the same sequence. Or, we explicitly say they may be different even if seeded identically (but why would we say that?). As to default seed, perhaps we could suggest vendors seed the generators differently so that different images give different streams? Aleks -- Aleksandar Donev, Ph.D. Luis W. Alvarez Postdoctoral Fellow Center for Computational Sciences and Engineering (https://ccse.lbl.gov) Lawrence Berkeley National Laboratory (http://www.lbl.gov) E-mail: adonev@lbl.gov Phone: (510) 486-5782 Fax: (510) 486-6900 Address: MS 50A-1148, LBL, 1 Cyclotron Rd., Berkeley, CA 94720 Web: http://cims.nyu.edu/~donev/