From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Hans Aberg Newsgroups: gmane.lisp.guile.devel Subject: Re: RFC: Arbitrary-precision floats for Guile Date: Wed, 2 Feb 2011 15:30:54 +0100 Message-ID: References: <878vxzx3g3.fsf@yeeloong.netris.org> NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 (Apple Message framework v936) Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes Content-Transfer-Encoding: 7bit X-Trace: dough.gmane.org 1296660076 18539 80.91.229.12 (2 Feb 2011 15:21:16 GMT) X-Complaints-To: usenet@dough.gmane.org NNTP-Posting-Date: Wed, 2 Feb 2011 15:21:16 +0000 (UTC) Cc: Mark H Weaver , guile-devel@gnu.org To: Andy Wingo Original-X-From: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Wed Feb 02 16:21:12 2011 Return-path: Envelope-to: guile-devel@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by lo.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1PkeW0-0005A7-Ut for guile-devel@m.gmane.org; Wed, 02 Feb 2011 16:21:05 +0100 Original-Received: from localhost ([127.0.0.1]:37845 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PkeVy-0003lj-Vq for guile-devel@m.gmane.org; Wed, 02 Feb 2011 10:21:04 -0500 Original-Received: from [140.186.70.92] (port=53107 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Pkdjr-0002wp-9O for guile-devel@gnu.org; Wed, 02 Feb 2011 09:31:24 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Pkdjk-0001km-37 for guile-devel@gnu.org; Wed, 02 Feb 2011 09:31:16 -0500 Original-Received: from smtp-out12.han.skanova.net ([195.67.226.212]:54006) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Pkdjj-0001i5-Pe for guile-devel@gnu.org; Wed, 02 Feb 2011 09:31:12 -0500 Original-Received: from [192.168.2.5] (217.210.127.13) by smtp-out12.han.skanova.net (8.5.133) (authenticated as u26619196) id 4D065C2900D5AFF7; Wed, 2 Feb 2011 15:30:57 +0100 In-Reply-To: X-Mailer: Apple Mail (2.936) X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 195.67.226.212 X-BeenThere: guile-devel@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "Developers list for Guile, the GNU extensibility library" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Errors-To: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.lisp.guile.devel:11509 Archived-At: On 1 Feb 2011, at 21:37, Andy Wingo wrote: > In (* inum flonum bigflonum), with what precision would the first > multiplication be performed? Note that currently the compiler > compiles > it as (* (* inum flonum) bigflownum). An idea that comes to my mind is to set a minimum float precision, which might be IEEE 64-bit or corresponding. Then, for multiprecision floats, I think a user-friendly solution would be the output precision of an operation being a function of the operation and the precision of the values put to it based on an error analysis with a margin, as to not introduce too big round-off errors. Experts might want to have something else, but that would be less user-friendly.