Return-Path: Received: by vger.rutgers.edu via listexpand id ; Thu, 23 Dec 1999 20:38:52 -0500 Received: by vger.rutgers.edu id ; Thu, 23 Dec 1999 20:38:29 -0500 Received: from vpws62.vpplus.com ([207.49.240.62]:22587 "EHLO quark.vpplus.com") by vger.rutgers.edu with ESMTP id ; Thu, 23 Dec 1999 20:38:11 -0500 Message-ID: <3862D177.F1EC9124@quark.vpplus.com> Date: Thu, 23 Dec 1999 20:50:47 -0500 From: Brian Gerst X-Mailer: Mozilla 4.61 [en] (X11; U; Linux 2.2.12-20 i586) X-Accept-Language: en MIME-Version: 1.0 To: Linux kernel mailing list Subject: Re: Linux Kernel Floating Point Emulation and CORDIC References: <99122316092902.01246@cel2> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-linux-kernel@vger.rutgers.edu Content-Length: 1213 Lines: 28 Arthur Jerijian wrote: > > 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 I don't think it's worth the effort to rewrite and retest the FP emulation code. It is only needed on some 386 and 486 machines, as all pentiums and later always have built in FPUs. Nobody should be doing any serious number crunching on those old processors. Just my 2 cents though. -- Brian Gerst - 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/