From owner-freebsd-current Tue Feb 4 6:22: 8 2003 Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id C79D137B401 for ; Tue, 4 Feb 2003 06:22:06 -0800 (PST) Received: from flood.ping.uio.no (flood.ping.uio.no [129.240.78.31]) by mx1.FreeBSD.org (Postfix) with ESMTP id 18ADC43F79 for ; Tue, 4 Feb 2003 06:22:06 -0800 (PST) (envelope-from des@ofug.org) Received: by flood.ping.uio.no (Postfix, from userid 2602) id 4BFC0536F; Tue, 4 Feb 2003 15:22:04 +0100 (CET) X-URL: http://www.ofug.org/~des/ X-Disclaimer: The views expressed in this message do not necessarily coincide with those of any organisation or company with which I am or have been affiliated. To: "Andrey A. Chernov" Cc: David Schultz , Kris Kennaway , current@FreeBSD.ORG Subject: Re: rand() is broken From: Dag-Erling Smorgrav Date: Tue, 04 Feb 2003 15:22:03 +0100 In-Reply-To: <20030204140806.GA93236@nagual.pp.ru> ("Andrey A. Chernov"'s message of "Tue, 4 Feb 2003 17:08:06 +0300") Message-ID: User-Agent: Gnus/5.090014 (Oort Gnus v0.14) Emacs/21.2 (i386--freebsd) References: <20030203002639.GB44914@HAL9000.homeunix.com> <20030203100002.GA73386@nagual.pp.ru> <20030204054020.GA2447@HAL9000.homeunix.com> <20030204094659.GA87303@nagual.pp.ru> <20030204115237.GA6483@HAL9000.homeunix.com> <20030204131006.GB92301@nagual.pp.ru> <20030204131748.GA92510@nagual.pp.ru> <20030204132845.GA92674@nagual.pp.ru> <20030204134714.GA92940@nagual.pp.ru> <20030204140806.GA93236@nagual.pp.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG "Andrey A. Chernov" writes: > With NSHUFF 100 situation not changed much, so I beleive that stated > problem is common for this type PRNGs, so we gains nothing changing > formulae to Knuth-recommended values. Yes we do. We get a better sequence for any given seed, i.e. we get less correlation between n and x(n) for any given x(0). I don't think it changes much for long sequences, but we get a better distribution for short sequences (including short subsequences of long sequences). As for patterns in the lower bits, we should try with a != 0 and see how that affects the results. I believe the purpose of a in the LCG algorithm is to scramble the lower bits. DES -- Dag-Erling Smorgrav - des@ofug.org To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message