From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 18279 invoked by alias); 6 Jul 2007 11:28:51 -0000 Received: (qmail 18271 invoked by uid 22791); 6 Jul 2007 11:28:50 -0000 X-Spam-Check-By: sourceware.org Received: from ch-smtp01.sth.basefarm.net (HELO ch-smtp01.sth.basefarm.net) (80.76.149.212) by sourceware.org (qpsmtpd/0.31) with ESMTP; Fri, 06 Jul 2007 11:28:45 +0000 Received: from c213-89-102-190.bredband.comhem.se ([213.89.102.190]:32978 helo=[192.168.0.2]) by ch-smtp01.sth.basefarm.net with esmtp (Exim 4.66) (envelope-from ) id 1I6lzP-0001G7-4V for gsl-discuss@sourceware.org; Fri, 06 Jul 2007 13:28:43 +0200 Mime-Version: 1.0 (Apple Message framework v752.2) Content-Transfer-Encoding: 7bit Message-Id: <51527A8D-FCAB-4251-95D6-F87ED8B5E769@comhem.se> Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed To: gsl-discuss@sourceware.org From: Tommy Nordgren Subject: Optimizing function calls in GSL Vegas Date: Fri, 06 Jul 2007 11:28:00 -0000 X-Mailer: Apple Mail (2.752.2) X-Scan-Result: No virus found in message 1I6lzP-0001G7-4V. 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: 2007-q3/txt/msg00006.txt.bz2 I want to compute a complicated integral with Vegas. The integral is 6-dimensional, and have a sinusoidal factor in a linear combination of the integration variables. The integration variables vary from negative to positive infinity. I can't solve this integral by simply using a coordinate substitution that will turn each integration range to a finite range, because then the sinusoidal factor will become pathologial. Instead, I use a generalized spherical coordinate transformation, which will turn the integration interval into a finite interval, for 5 of the integration variables, where the function called by vegas is computed as a Fourier integral with respect to the radial parameter. My problem is choosing good heuristics, for estimating to what relative and absolute accuracy to use as parameters to the Fourier integral. ------------------------------------------------------ "Home is not where you are born, but where your heart finds peace" - Tommy Nordgren, "The dying old crone" tommy.nordgren@comhem.se