From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 14520 invoked by alias); 31 Jan 2003 17:33:06 -0000 Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Archive: List-Post: List-Help: Sender: gcc-owner@gcc.gnu.org Received: (qmail 14461 invoked from network); 31 Jan 2003 17:33:03 -0000 Received: from unknown (HELO sungoddess.ccs.yorku.ca) (130.63.236.144) by 172.16.49.205 with SMTP; 31 Jan 2003 17:33:03 -0000 Received: from yorku.ca (poison.cvr.yorku.ca [130.63.188.161]) by sungoddess.ccs.yorku.ca (8.9.3/8.9.3) with ESMTP id MAA13020; Fri, 31 Jan 2003 12:32:55 -0500 (EST) Message-ID: <3E3AB250.E768304D@yorku.ca> Date: Fri, 31 Jan 2003 18:44:00 -0000 From: Bob Hou X-Accept-Language: en MIME-Version: 1.0 To: gcc@gnu.org, gcc@gcc.gnu.org, yhou@YorkU.CA Subject: double error Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-SW-Source: 2003-01/txt/msg01780.txt.bz2 Hi, I have the following simple code and expect the results are all the same. However the output is following: (The code is compiled with gcc under Redhat8.0. ) The result is : 0 The result is : 0 The result is : -2.22045e-15 The code is also tested on MS VS6.0 and it give the same answers (zero). Could you tell me whether it's a bug or I did sth wrong? Thanks, /*--------------- test.c---------------------------*/ #include int main() { double fi = 0.7509; double fj = 100.0; double fk, fk1, fk2 ; fk = fj*fi - fj*fi; fk1 = 0.7509*100.0 - 0.7509*100.0; fk2 = fj*fi - 0.7509*100.0; printf("The result is : %g\n", fk); printf("The result is : %g\n", fk1); printf("The result is : %g\n", fk2); return 0; } /*-----------------end-----------------------------*/ -- __________________________________________________________ Dr. Bob (Yuqian) Hou Certre for Vision Research Rm0002B, CSB York University 4700 Keele Street North York, Ontario Canada M3J 1P3 Tel: (416) 736-2100 ext. 66117 Fax: (416) 736-5814 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 20009 invoked by alias); 31 Jan 2003 17:38:59 -0000 Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Archive: List-Post: List-Help: Sender: gcc-owner@gcc.gnu.org Received: (qmail 20001 invoked from network); 31 Jan 2003 17:38:58 -0000 Received: from unknown (HELO fencepost.gnu.org) (199.232.76.164) by 172.16.49.205 with SMTP; 31 Jan 2003 17:38:58 -0000 Received: from monty-python.gnu.org ([199.232.76.173]) by fencepost.gnu.org with esmtp (Exim 4.10) id 18ef7y-000766-00 for gcc@gnu.org; Fri, 31 Jan 2003 12:38:58 -0500 Received: from mail by monty-python.gnu.org with spam-scanned (Exim 4.10.13) id 18ef2t-0000q7-00 for gcc@gnu.org; Fri, 31 Jan 2003 12:33:43 -0500 Received: from sungoddess.ccs.yorku.ca ([130.63.236.144]) by monty-python.gnu.org with esmtp (Exim 4.10.13) id 18ef2E-0000SV-00 for gcc@gnu.org; Fri, 31 Jan 2003 12:33:02 -0500 Received: from yorku.ca (poison.cvr.yorku.ca [130.63.188.161]) by sungoddess.ccs.yorku.ca (8.9.3/8.9.3) with ESMTP id MAA13020; Fri, 31 Jan 2003 12:32:55 -0500 (EST) Message-ID: <3E3AB250.E768304D@yorku.ca> Date: Fri, 31 Jan 2003 19:01:00 -0000 From: Bob Hou X-Accept-Language: en MIME-Version: 1.0 To: gcc@gnu.org, gcc@gcc.gnu.org, yhou@YorkU.CA Subject: double error Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Spam-Status: No, hits=0.2 required=5.0 tests=SPAM_PHRASE_00_01,X_ACCEPT_LANG version=2.41 X-Spam-Level: X-SW-Source: 2003-01/txt/msg01783.txt.bz2 Message-ID: <20030131190100.iHIvzoAJfA_f5OR_6-X96VjhjBrfK4gPpGDBRpRCY_c@z> Hi, I have the following simple code and expect the results are all the same. However the output is following: (The code is compiled with gcc under Redhat8.0. ) The result is : 0 The result is : 0 The result is : -2.22045e-15 The code is also tested on MS VS6.0 and it give the same answers (zero). Could you tell me whether it's a bug or I did sth wrong? Thanks, /*--------------- test.c---------------------------*/ #include int main() { double fi = 0.7509; double fj = 100.0; double fk, fk1, fk2 ; fk = fj*fi - fj*fi; fk1 = 0.7509*100.0 - 0.7509*100.0; fk2 = fj*fi - 0.7509*100.0; printf("The result is : %g\n", fk); printf("The result is : %g\n", fk1); printf("The result is : %g\n", fk2); return 0; } /*-----------------end-----------------------------*/ -- __________________________________________________________ Dr. Bob (Yuqian) Hou Certre for Vision Research Rm0002B, CSB York University 4700 Keele Street North York, Ontario Canada M3J 1P3 Tel: (416) 736-2100 ext. 66117 Fax: (416) 736-5814