From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 18356 invoked by alias); 15 Dec 2009 17:31:37 -0000 Received: (qmail 18346 invoked by uid 22791); 15 Dec 2009 17:31:36 -0000 X-SWARE-Spam-Status: No, hits=-1.4 required=5.0 tests=AWL,BAYES_00,SARE_MSGID_LONG40,SPF_PASS X-Spam-Check-By: sourceware.org Received: from mail-bw0-f219.google.com (HELO mail-bw0-f219.google.com) (209.85.218.219) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Tue, 15 Dec 2009 17:31:32 +0000 Received: by bwz19 with SMTP id 19so118598bwz.8 for ; Tue, 15 Dec 2009 09:31:30 -0800 (PST) MIME-Version: 1.0 Received: by 10.204.36.194 with SMTP id u2mr3874032bkd.138.1260898290133; Tue, 15 Dec 2009 09:31:30 -0800 (PST) In-Reply-To: <87d42ggnsv.wl%bjg@network-theory.co.uk> References: <4a00655d0908201247g7d7bd9a1t466f4a66f08df4@mail.gmail.com> <4a00655d0911291536t5a11752fp27ab9c274148f822@mail.gmail.com> <4a00655d0911291538y9f29830v984d1a796fdd5d1@mail.gmail.com> <4a00655d0912131549w19638273nb51d723e9ddd9273@mail.gmail.com> <87d42ggnsv.wl%bjg@network-theory.co.uk> From: Rhys Ulerich Date: Tue, 15 Dec 2009 17:31:00 -0000 Message-ID: <4a00655d0912150931q4b34fd24p94594ed08857254f@mail.gmail.com> Subject: Re: Where a generalized Richardson extrapolation routine would fit in GSL? To: Brian Gough Cc: gsl-discuss@sourceware.org Content-Type: text/plain; charset=ISO-8859-1 Mailing-List: contact gsl-discuss-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gsl-discuss-owner@sourceware.org X-SW-Source: 2009-q4/txt/msg00062.txt.bz2 Thanks for looking through the patch Brian. > One question: it looks like this > extrapolates a vector quantity. For simplicity, would it make sense > to work with scalars as in the gsl_sum routines -- since presumably > that is the common case -- or is there some application where vector > extrapolation is unavoidable? (could each component can be > extrapolated independently?) You're right that each component could be extrapolated independently. I wrote it using vectors because doing so allows using BLAS calls for the linear algebra and speeds up many component use cases. I'd prefer to keep the code vector-capable under the covers under the theory that people extrapolating only a scalar at a time aren't all that worried about speed. My vector use case arose from testing convergence orders for timesteppers (non-GSL, but similar in interface) that manipulate vectors of state variables. If you'd like, I can submit an additional patch that 1) Renames gsl_extrap_richardson to something like gsl_extrap_richardson_vector, 2) Provides a scalar-only gsl_extrap_richardson that wraps up scalars and calls the gsl_extrap_richardson_vector routines under the covers, and 3) Exercises the scalar-only wrappers fully in the test suite. That way if someone later does need a faster scalar-only version, he or she can change over the underlying implementation without fear of regression. - Rhys