Send mail to: mgnet@cs.yale.edu for the digests mgnet-requests@cs.yale.edu for comments or help Anonymous ftp repository: casper.cs.yale.edu (128.36.12.1) Today's editor: Craig Douglas (douglas-craig@cs.yale.edu) Volume 2, Number 7 (July 29, 1992) Today's topics: Question about multigrid for unstructured grids Summary of workshop on C++ Seventh Conference on Domain Decomposition Methods Paper entitled Kinematics of Multigrid Monte Carlo MADPACK Status (versions 2 and 4 available) Incoming directory status ------------------------------------------------------- Date: Fri, 19 Jun 92 10:10:08 -0700 From: simon@nas.nasa.gov (Horst D. Simon) Subject: question for mgnet readers I would like to find out what ideas have been proposed or implemented in the area of multigrid for unstructured grids. In particular I would like to obtain references about algorithms for coarsening existing unstructured grids. But any general references about unstructured multigrid would be useful as well. Horst Simon Editor's Note: I think many readers would like to know this, too. ------------- Please cc this list. ------------------------------------------------------- From: Ulrich Ruede Subject: Summary of workshop on C++ On April 14th, at the Copper Mountain SIAM conference on iterative methods, a workshop was held to present C++ as a useful language for Scientific Computing. The workshop was organized by Dan Quinlan and included a panel of seven participants: Dinshaw Balsara, from Johns Hopkins University; Doug Clarkson, president of Dyad Software Corporation (developers of the M++ array class library); Carl Kesselman, from Caltech; James S. Peery, from Sandia National Laboratory; Daniel Quinlan, from University of Colorado at Denver; Allen C. Robinson, from Sandia National Laboratory; and Ulrich Ruede, from Technische Universitaet Muenchen. C++ as a language for scientific computing has recently been gaining increased attention. Besides providing the programming concepts of an advanced language it can be highly efficient, is widely available and is very portable. Its features make it almost ideally suited for the tasks in mathematical and scientific software development. The class concept and operator overloading make the language extensible so that user defined data structures can be handled the same way as built-in data types. Thus all the FORTRAN-90 array language functionality can be provided on the library level. Similarly, most standardization problems for numerical libraries in FORTRAN would be much easier in C++, because the abstraction mechanisms of C++ allow more natural library interfaces that are not obscured by work-arounds for language deficiencies. A brief summary of the workshop is available by ftp from the mgnet server. Ulrich Ruede ------------------------------------------------------- From: Jinchao Xu Date: Tue, 28 Jul 92 16:17:22 -0400 Subject: Seventh Conference on Domain Decomposition Methods The Seventh International Conference on Domain Decomposition Methods will be held at Penn State during the four day period October 27-30, 1993. If you want to receive further information, please contact: R. Manning (secretary), Dept. of Math., Penn State Univ., University Park, PA 16802. Tel: 814-865-7527; Fax: 814-865-3735; Email: ddm7@math.psu.edu. ------------------------------------------------------- From: Martin Grabenstein Date: Wed, 29 Jul 92 10:09:29 MESZ Subject: Paper entitled Kinematics of Multigrid Monte Carlo Kinematics of Multigrid Monte Carlo, M.Grabenstein and K.Pinn, 28 pages, 8 ps-figures, preprint DESY 92-094 Abstract: We study the kinematics of multigrid Monte Carlo algorithms by means of acceptance rates for nonlocal Metropolis update proposals. An approximation formula for acceptance rates is derived. We present a comparison of different coarse-to-fine interpolation schemes in free field theory, where the formula is exact. The predictions of the approximation formula for several interacting models are well confirmed by Monte Carlo simulations. The following rule is found: For a critical model with fundamental Hamiltonian H(phi), absence of critical slowing down can only be expected if the expansion of in terms of the shift psi contains no relevant (mass) term. We also introduce a multigrid update procedure for nonabelian lattice gauge theory and study the acceptance rates for gauge group SU(2) in four dimensions. Editor's Note: Installed in the papers/Grabenstein-Pinn directory. ------------- ------------------------------------------------------- From: Craig Douglas Subject: MADPACK Status (versions 2 and 4 available) I have moved version 2 of madpack (the public domain version) to the directory madpack2 and have installed a madpack4 directory with the recently released IBM copyrighted codes damg and dpmg. There is a short questionaire associated with version 4 that I hope people will fill out even if they decide not use the codes. This should be returned to me at Yale, not IBM. This is for my benefit. If there is enough interest, I will put a summary in the madpack4 directory. Note that the documentation files are not present in version 4. There are several thousand lines of comments at the head of both programs that should help. Anyone serious about using these codes should contact me for preliminary LaTeX files that provide a little more insight. (I did not want to waste my time writing papers if the codes were not going to be released to the public in source form.) ------------------------------------------------------- From: Craig Douglas Subject: Incoming directory status I have opened the mgnet/incoming directory again. I will have to shut it down whenever I am out of town. So, please start putting objects there again, except during August 1-7... While I am on sabbatical full time at Yale this year, things should work better than they have the past two months. My apologies to those who have had difficulties this month in particular. ------------------------------ End of MGNet Digest **************************