From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by vger.rutgers.edu via listexpand id ; Fri, 24 Dec 1999 17:54:38 -0500 Received: by vger.rutgers.edu id ; Fri, 24 Dec 1999 17:54:19 -0500 Received: from amdext2.amd.com ([163.181.251.1]:35858 "EHLO amdext2.amd.com") by vger.rutgers.edu with ESMTP id ; Fri, 24 Dec 1999 17:54:00 -0500 From: nathan.zook@amd.com Message-ID: To: lightmanaj@earthlink.net, linux-kernel@vger.rutgers.edu Subject: RE: Linux Kernel Floating Point Emulation and CORDIC Date: Fri, 24 Dec 1999 16:53:56 -0600 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2650.21) Content-Type: text/plain Sender: owner-linux-kernel@vger.rutgers.edu EEEEEwwww! Cordic is UGLY! There is a reason that Intel & we (AMD) have gone with polyonmial & rational function approximations. BTW, our algorithms are quite accurate. If you are running in another world, or just want to emulate, look into equal-ripple approximations. You will chew some serious processor power finding good functions, but what you get can be nice. Nathan > -----Original Message----- > From: Arthur Jerijian [SMTP:lightmanaj@earthlink.net] > Sent: Thursday, December 23, 1999 5:58 PM > To: linux-kernel@vger.rutgers.edu > Subject: Linux Kernel Floating Point Emulation and CORDIC > > For the mathematics and theoretical computer science enthusiasts here on > this > list: > > I have taken a look at the source code of the Linux Kernel floating point > emulation engine for i386 (as of 2.2.12, don't know if it changed in > 2.3.x). I > noticed that it uses Taylor/Maclaurin polynomials to approximate the sine, > cosine, tangent, and inverse tangent functions. Wouldn't CORDIC be a > better > algorithm for computing trigonometric and exponential functions instead? > CORDIC > is a method for calculating mathematical functions using only addition, > shifting, and looking up entries in a table. More details can be found at > http://www.ezcomm.com/%7Ecyliax/Articles/RobNav/sidebar.html > > Thanks, > --Arthur > > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.rutgers.edu > Please read the FAQ at http://www.tux.org/lkml/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/