From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 29456 invoked by alias); 4 Mar 2012 07:02:34 -0000 Received: (qmail 29444 invoked by uid 22791); 4 Mar 2012 07:02:32 -0000 X-SWARE-Spam-Status: No, hits=-2.6 required=5.0 tests=AWL,BAYES_00,DKIM_SIGNED,DKIM_VALID,FREEMAIL_FROM,RCVD_IN_DNSWL_LOW X-Spam-Check-By: sourceware.org Received: from mail-bk0-f41.google.com (HELO mail-bk0-f41.google.com) (209.85.214.41) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Sun, 04 Mar 2012 07:02:16 +0000 Received: by bkwq16 with SMTP id q16so2999108bkw.0 for ; Sat, 03 Mar 2012 23:02:15 -0800 (PST) Received-SPF: pass (google.com: domain of tuomo.keskitalo@gmail.com designates 10.204.156.77 as permitted sender) client-ip=10.204.156.77; Authentication-Results: mr.google.com; spf=pass (google.com: domain of tuomo.keskitalo@gmail.com designates 10.204.156.77 as permitted sender) smtp.mail=tuomo.keskitalo@gmail.com; dkim=pass header.i=tuomo.keskitalo@gmail.com Received: from mr.google.com ([10.204.156.77]) by 10.204.156.77 with SMTP id v13mr8570287bkw.112.1330844535618 (num_hops = 1); Sat, 03 Mar 2012 23:02:15 -0800 (PST) MIME-Version: 1.0 Received: by 10.204.156.77 with SMTP id v13mr6816746bkw.112.1330844535375; Sat, 03 Mar 2012 23:02:15 -0800 (PST) Received: by 10.204.226.205 with HTTP; Sat, 3 Mar 2012 23:02:15 -0800 (PST) In-Reply-To: <4F50F1BE.10603@colorado.edu> References: <4F50F1BE.10603@colorado.edu> Date: Sun, 04 Mar 2012 07:02:00 -0000 Message-ID: Subject: Re: odeiv2 request From: Tuomo Keskitalo To: Patrick Alken 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: 2012-q1/txt/msg00018.txt.bz2 Hello, that's an interesting use case. May I ask why you needed to integrate backwards? Did you use driver_apply for integration? I haven't really considered anyone "hotswapping" the direction of integration using driver functions.. I think that the stepper at least must be reset if integration direction is changed, to be safe with multistep methods. This needs some thinking and testing. I can try to see to this in a week or few. Tuomo On Fri, Mar 2, 2012 at 6:13 PM, Patrick Alken wrote: > I had a problem recently where I needed to integrate forward along a curve > (positive step size h) and then integrate backward again (negative h). But > there is currently no way to change the sign of the step size h using the > driver routines, so I had to modify driver->h directly. > > I propose adding a routine gsl_odeiv2_driver_set_h() to allow the user to > reset the step size to what they want. Tuomo: do you see any negative issues > with this? I can make the addition if you want. > > Thanks, > Patrick -- Tuomo.Keskitalo@iki.fi http://iki.fi/tuomo.keskitalo