From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Hengqing Hu Newsgroups: gmane.lisp.guile.user Subject: Can somebody help to explain why result from atan does not equal a real? Date: Thu, 31 Jan 2013 18:50:43 +0800 Message-ID: NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 X-Trace: ger.gmane.org 1359629455 26934 80.91.229.3 (31 Jan 2013 10:50:55 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 31 Jan 2013 10:50:55 +0000 (UTC) To: guile-user@gnu.org Original-X-From: guile-user-bounces+guile-user=m.gmane.org@gnu.org Thu Jan 31 11:51:15 2013 Return-path: Envelope-to: guile-user@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1U0rje-0007om-Su for guile-user@m.gmane.org; Thu, 31 Jan 2013 11:51:15 +0100 Original-Received: from localhost ([::1]:46001 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1U0rjM-00060e-IV for guile-user@m.gmane.org; Thu, 31 Jan 2013 05:50:56 -0500 Original-Received: from eggs.gnu.org ([208.118.235.92]:37220) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1U0rjE-00060X-9r for guile-user@gnu.org; Thu, 31 Jan 2013 05:50:53 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1U0rjB-000354-DY for guile-user@gnu.org; Thu, 31 Jan 2013 05:50:48 -0500 Original-Received: from mail-ob0-f174.google.com ([209.85.214.174]:37240) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1U0rjA-00034Z-K6 for guile-user@gnu.org; Thu, 31 Jan 2013 05:50:45 -0500 Original-Received: by mail-ob0-f174.google.com with SMTP id 16so2742367obc.33 for ; Thu, 31 Jan 2013 02:50:43 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:x-received:date:message-id:subject:from:to :content-type; bh=6SMRJX8XK8yStcwOEjZr3fp5igTPfXgcxMvcIx9bJoU=; b=quhJ+oysoM6lSuHHSSF2xWQJ5MCeTNMs3yxdycB6fszLAXQhBhgiRNWhMW3EJD97lb y3rj5bxNQ9qk0gWG34z2FSa3FxQCXpnGp7GzPRyCZyluxfVzubPXJO6qhZyz+bHhU8vn L3gFJAIWmpZcMaWfEgY8TJ21YSMhDrYtAwEXbHhyvL7jZukTIWkK0yElJ8aZVO2Pg7Z5 4bWV/jtx6abkXOR1LJZEUiCIMKZX667S/Sb+qrW90cRlSFFhLhdbhiKxdRpamDnmjUhE +Czh8E1+yVv8mw9mHJsFgam4GC4DA+FyDj+HzjWH9jmApzvEsgQELFkZdZ1M18w68isV CDNg== X-Received: by 10.182.144.40 with SMTP id sj8mr6020258obb.82.1359629443622; Thu, 31 Jan 2013 02:50:43 -0800 (PST) Original-Received: by 10.60.29.230 with HTTP; Thu, 31 Jan 2013 02:50:43 -0800 (PST) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [fuzzy] X-Received-From: 209.85.214.174 X-BeenThere: guile-user@gnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: General Guile related discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: guile-user-bounces+guile-user=m.gmane.org@gnu.org Original-Sender: guile-user-bounces+guile-user=m.gmane.org@gnu.org Xref: news.gmane.org gmane.lisp.guile.user:9951 Archived-At: Dear list, The following behavior is observed on both guile 1.8 and guile 2.0. Is it correct? Can somebody elaborate why it happens? guile> (atan 0 -1) 3.14159265358979 guile> (= 3.14159265358979 3.14159265358979) #t guile> (= (atan 0 -1) 3.14159265358979) #f -- Best Regards, Hengqing Hu