From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: David Kastrup Newsgroups: gmane.lisp.guile.devel Subject: Re: Improve `seed->random-state' in stable-2.0? Date: Fri, 20 Jan 2012 09:37:21 +0100 Organization: Organization?!? Message-ID: <87zkdin51a.fsf@fencepost.gnu.org> References: <87d3afvyr6.fsf@netris.org> NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: dough.gmane.org 1327048673 27679 80.91.229.12 (20 Jan 2012 08:37:53 GMT) X-Complaints-To: usenet@dough.gmane.org NNTP-Posting-Date: Fri, 20 Jan 2012 08:37:53 +0000 (UTC) To: guile-devel@gnu.org Original-X-From: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Fri Jan 20 09:37:50 2012 Return-path: Envelope-to: guile-devel@m.gmane.org Original-Received: from lists.gnu.org ([140.186.70.17]) by lo.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1Ro9yn-0001Mf-J6 for guile-devel@m.gmane.org; Fri, 20 Jan 2012 09:37:49 +0100 Original-Received: from localhost ([::1]:45874 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Ro9ym-0002d8-Oy for guile-devel@m.gmane.org; Fri, 20 Jan 2012 03:37:48 -0500 Original-Received: from eggs.gnu.org ([140.186.70.92]:59467) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Ro9yh-0002cy-NR for guile-devel@gnu.org; Fri, 20 Jan 2012 03:37:47 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Ro9yd-0005j9-Nr for guile-devel@gnu.org; Fri, 20 Jan 2012 03:37:43 -0500 Original-Received: from lo.gmane.org ([80.91.229.12]:44727) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Ro9yd-0005it-In for guile-devel@gnu.org; Fri, 20 Jan 2012 03:37:39 -0500 Original-Received: from list by lo.gmane.org with local (Exim 4.69) (envelope-from ) id 1Ro9yZ-0001EF-01 for guile-devel@gnu.org; Fri, 20 Jan 2012 09:37:35 +0100 Original-Received: from p508edacf.dip.t-dialin.net ([80.142.218.207]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Fri, 20 Jan 2012 09:37:34 +0100 Original-Received: from dak by p508edacf.dip.t-dialin.net with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Fri, 20 Jan 2012 09:37:34 +0100 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 16 Original-X-Complaints-To: usenet@dough.gmane.org X-Gmane-NNTP-Posting-Host: p508edacf.dip.t-dialin.net X-Face: 2FEFf>]>q>2iw=B6, xrUubRI>pR&Ml9=ao@P@i)L:\urd*t9M~y1^:+Y]'C0~{mAl`oQuAl \!3KEIp?*w`|bL5qr,H)LFO6Q=qx~iH4DN; i"; /yuIsqbLLCh/!U#X[S~(5eZ41to5f%E@'ELIi$t^ Vc\LWP@J5p^rst0+('>Er0=^1{]M9!p?&:\z]|;&=NP3AhB!B_bi^]Pfkw User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.0.92 (gnu/linux) Cancel-Lock: sha1:se95tlzo1bYfHP6aAmKTOTUSaeM= X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6 (newer, 3) X-Received-From: 80.91.229.12 X-BeenThere: guile-devel@gnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: "Developers list for Guile, the GNU extensibility library" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Original-Sender: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.lisp.guile.devel:13594 Archived-At: Mark H Weaver writes: > I know how to make this _much_ better, but here's the question: is it > okay to change the behavior of the random number generator in 2.0? Or > is it important that the same sequence of random numbers are generated > from a given seed in the entire stable-2.0 series? As long as the total _sequence_ stays the same (and does not contain duplicate values), I would not worry. If the sequence itself becomes different, then the probability of two random subsequences having at least one match match grows with the product rather than the sum of their length. Of course, if the subsequences _do_ overlap, you tend to get colliding sequences instead of just single outliers. -- David Kastrup