simulation@uflorida.cis.ufl.edu (Moderator: Paul Fishwick) (07/15/89)
Volume: 10, Issue: 1, Fri Jul 14 15:11:31 EDT 1989 +----------------+ | TODAY'S TOPICS | +----------------+ (1) Event Scheduling and Cancellation (2) Adomian's Decomposition Method (3) SMPL Porting Experience * Moderator: Paul Fishwick, Univ. of Florida * Send topical mail to: simulation@uflorida.cis.ufl.edu * Archives available via FTP to bikini.cis.ufl.edu, login as 'anonymous', use your last name as the password, change directory to pub/simdigest. * Simulation Tools available by doing above and changing the directory to pub/simdigest/tools. ----------------------------------------------------------------------------- Date: Thu, 13 Jul 89 09:22:40 -0400 >From srcnance Tue Jun 6 08:50:17 1989 To: vtodie!simulation@bikini.cis.ufl.edu Like Mike Overstreet, I too would like to see a copy of your paper on event cancellation. I suspect that we may have a difference in perceptions that is coloring our assumptions about what information is held by the simulation executive. The context of interactive discrete event simulation makes this an understandable need. Obviously, the clock must be "turned back" in parallel simulations using an optimistic protocol, e.g. Time-Warp, MTW. But this is not a truly reversible execution; rather it calls for breakpoint and recovery capability that has received considerable attention in the operating systems literature addressing highly reliable systems. Consider a more intriguing question (at least to me): Given a state S, what sequence of events could have led to this state? Is that sequence unique? What is the minimum subset of events in the sequence whose elimination would have prevented S (either at time t or at any time? It seems to me that these questions are more indicative of a need for true reversibility. The domain of model explanation, which has arisen in AI, would seem to address the subsequent questions of sequence uniqueness or state prevention noted above. Dick Nance nance@vtopus.cs.vt.edu ------------------------------ Date: Thu, 13 Jul 89 11:29:24 EDT From: Gulam Samdani <gsa2_ss@uhura.cc.rochester.edu> To: simulation@bikini.cis.ufl.edu Dear netters: This is to ask for the benefit of experience of those people who have used or heard about Adomian's Decomposition Method developed by Prof. George Adomian at the University of Georgia and quite broadly publicized through his three recent books, namely "Stochastic Systems", "Partial Differential Equations: New Methods for Their Treatment and Solution" and "Nonlinear Stochastic Operator Equations". Personally I fell in love with his style of mathematical exposition: clear and always provocative. Has anybody used this Method to solve any 'real' problem? When I first came across his work, I was very much mesmerized by the power of the method; especially the examples he presented in his books and journal articles. However, I am running into some difficulty since I have attempted to apply it to one of my dissertation problems! I think the problem is due to slow convergence resulting from the successive approximation nature of the Method. Has anybody in the Net experienced anything of this sort? I also wonder how 'well-known' is the Method now to the applied mathematics community? The only 'standard' reference that has any reference to this Method is D. Zwillinger's "Handbook of Differential Equations (1989)". I would appreciate any comment or criticism on the mathematical soundness of the Method itself. Thank you. G. Sam Samdani gsa2_ss@uhura.cc.rochester.edu ------------------------------ Date: Fri, 14 Jul 89 18:31 N From: Patrick Van Renterghem / Transputer Lab <PVR%AUTOCTRL.RUG.AC.BE@CUNYVM.CUNY.EDU> Subject: SMPL porting experience To: simulation-maillist@ufl.EDU X-Vms-To: IN%"simulation-maillist@ufl.edu" Comments: From: Patrick Van Renterghem, State University of Ghent References: > The Transputer Lab, Grotesteenweg Noord 2, +32 91 22 57 55 Keywords: > B-9710 Ghent-Zwijnaarde, Belgium, Europe. Fax: +32 91 22 85 91 Dear Simulationists, This is a short write-up on the porting of the SMPL program (which is available via ftp as described on this mailing list) to our Microvax II/VMS and to a transputer system. * Our C compiler complains about things like '=+' and '=*'. Although this can be easily solved by replacing them by '= +' and '= *', I would recommend to give your equal sign and expressions some more space. Eliminating blanks decreases readibility. * time () and pause () are already in the VAX library. I have replaced the smpl time and pause routines by smpl_time and smpl_pause. * Once these problems were solved, the program ran on the Microvax. We then ported the package to a single transputer system, mainly because we expected it to run a lot faster on a T800 transputer than on a MicroVAX or a PC/AT. And indeed it does. We used 3L's Parallel C and an Inmos B004 board with a T800 and 2 MBytes of slow memory. Naturally, our intention is to get the application running on several transputers. We know all about lockstep and time-warp approaches, but does anyone have an implementation of time-warp that we can use/adopt ??? * A number of questions remain: - are there any known bugs in smpl ? - is it public domain (can we pass it on ?) ? - would it be possible to have the smpl/PC and mtr () programs as well ? - does anyone have experience with parallelization of discrete event simulation on a distributed memory machine ? ***************************************************************************** * Patrick Van Renterghem, BITNET: pvr@bgerug51.bitnet * * R&D Assistant, EDU: pvr%bgerug51.bitnet@cunyvm.cuny.edu * * State University of Ghent UUCP: mcvax!bgerug51.bitnet!pvr * * Belgium JANET: PVR%earn.bgerug51@earn-relay * * * * Automatic Control Lab/The Transputer Lab, Tel: +32 91 22 57 55 ext. 313 * * State University of Ghent, Fax: +32 91 22 85 91 * * Grotesteenweg Noord 2, * * B-9710 Ghent-Zwijnaarde, Belgium * ***************************************************************************** ------------------------------ END OF SIMULATION DIGEST ************************