126 research outputs found
Preconditioned Spectral Clustering for Stochastic Block Partition Streaming Graph Challenge
Locally Optimal Block Preconditioned Conjugate Gradient (LOBPCG) is
demonstrated to efficiently solve eigenvalue problems for graph Laplacians that
appear in spectral clustering. For static graph partitioning, 10-20 iterations
of LOBPCG without preconditioning result in ~10x error reduction, enough to
achieve 100% correctness for all Challenge datasets with known truth
partitions, e.g., for graphs with 5K/.1M (50K/1M) Vertices/Edges in 2 (7)
seconds, compared to over 5,000 (30,000) seconds needed by the baseline Python
code. Our Python code 100% correctly determines 98 (160) clusters from the
Challenge static graphs with 0.5M (2M) vertices in 270 (1,700) seconds using
10GB (50GB) of memory. Our single-precision MATLAB code calculates the same
clusters at half time and memory. For streaming graph partitioning, LOBPCG is
initiated with approximate eigenvectors of the graph Laplacian already computed
for the previous graph, in many cases reducing 2-3 times the number of required
LOBPCG iterations, compared to the static case. Our spectral clustering is
generic, i.e. assuming nothing specific of the block model or streaming, used
to generate the graphs for the Challenge, in contrast to the base code.
Nevertheless, in 10-stage streaming comparison with the base code for the 5K
graph, the quality of our clusters is similar or better starting at stage 4 (7)
for emerging edging (snowballing) streaming, while the computations are over
100-1000 faster.Comment: 6 pages. To appear in Proceedings of the 2017 IEEE High Performance
Extreme Computing Conference. Student Innovation Award Streaming Graph
Challenge: Stochastic Block Partition, see
http://graphchallenge.mit.edu/champion
Block Locally Optimal Preconditioned Eigenvalue Xolvers (BLOPEX) in hypre and PETSc
We describe our software package Block Locally Optimal Preconditioned
Eigenvalue Xolvers (BLOPEX) publicly released recently. BLOPEX is available as
a stand-alone serial library, as an external package to PETSc (``Portable,
Extensible Toolkit for Scientific Computation'', a general purpose suite of
tools for the scalable solution of partial differential equations and related
problems developed by Argonne National Laboratory), and is also built into {\it
hypre} (``High Performance Preconditioners'', scalable linear solvers package
developed by Lawrence Livermore National Laboratory). The present BLOPEX
release includes only one solver--the Locally Optimal Block Preconditioned
Conjugate Gradient (LOBPCG) method for symmetric eigenvalue problems. {\it
hypre} provides users with advanced high-quality parallel preconditioners for
linear systems, in particular, with domain decomposition and multigrid
preconditioners. With BLOPEX, the same preconditioners can now be efficiently
used for symmetric eigenvalue problems. PETSc facilitates the integration of
independently developed application modules with strict attention to component
interoperability, and makes BLOPEX extremely easy to compile and use with
preconditioners that are available via PETSc. We present the LOBPCG algorithm
in BLOPEX for {\it hypre} and PETSc. We demonstrate numerically the scalability
of BLOPEX by testing it on a number of distributed and shared memory parallel
systems, including a Beowulf system, SUN Fire 880, an AMD dual-core Opteron
workstation, and IBM BlueGene/L supercomputer, using PETSc domain decomposition
and {\it hypre} multigrid preconditioning. We test BLOPEX on a model problem,
the standard 7-point finite-difference approximation of the 3-D Laplacian, with
the problem size in the range .Comment: Submitted to SIAM Journal on Scientific Computin
Understanding Quantum Technologies 2022
Understanding Quantum Technologies 2022 is a creative-commons ebook that
provides a unique 360 degrees overview of quantum technologies from science and
technology to geopolitical and societal issues. It covers quantum physics
history, quantum physics 101, gate-based quantum computing, quantum computing
engineering (including quantum error corrections and quantum computing
energetics), quantum computing hardware (all qubit types, including quantum
annealing and quantum simulation paradigms, history, science, research,
implementation and vendors), quantum enabling technologies (cryogenics, control
electronics, photonics, components fabs, raw materials), quantum computing
algorithms, software development tools and use cases, unconventional computing
(potential alternatives to quantum and classical computing), quantum
telecommunications and cryptography, quantum sensing, quantum technologies
around the world, quantum technologies societal impact and even quantum fake
sciences. The main audience are computer science engineers, developers and IT
specialists as well as quantum scientists and students who want to acquire a
global view of how quantum technologies work, and particularly quantum
computing. This version is an extensive update to the 2021 edition published in
October 2021.Comment: 1132 pages, 920 figures, Letter forma
Reports to the President
A compilation of annual reports for the 1985-1986 academic year, including a report from the President of the Massachusetts Institute of Technology, as well as reports from the academic and administrative units of the Institute. The reports outline the year's goals, accomplishments, honors and awards, and future plans
Law and Policy for the Quantum Age
Law and Policy for the Quantum Age is for readers interested in the political and business strategies underlying quantum sensing, computing, and communication. This work explains how these quantum technologies work, future national defense and legal landscapes for nations interested in strategic advantage, and paths to profit for companies
Software for Exascale Computing - SPPEXA 2016-2019
This open access book summarizes the research done and results obtained in the second funding phase of the Priority Program 1648 "Software for Exascale Computing" (SPPEXA) of the German Research Foundation (DFG) presented at the SPPEXA Symposium in Dresden during October 21-23, 2019. In that respect, it both represents a continuation of Vol. 113 in Springer’s series Lecture Notes in Computational Science and Engineering, the corresponding report of SPPEXA’s first funding phase, and provides an overview of SPPEXA’s contributions towards exascale computing in today's sumpercomputer technology. The individual chapters address one or more of the research directions (1) computational algorithms, (2) system software, (3) application software, (4) data management and exploration, (5) programming, and (6) software tools. The book has an interdisciplinary appeal: scholars from computational sub-fields in computer science, mathematics, physics, or engineering will find it of particular interest
4.Uluslararası Öğrenciler Fen Bilimleri Kongresi Bildiriler Kitabı
Çevrimiçi ( XIII, 495 Sayfa ; 26 cm.)
Reports to the President
A compilation of annual reports for the 1988-1989 academic year, including a report from the President of the Massachusetts Institute of Technology, as well as reports from the academic and administrative units of the Institute. The reports outline the year's goals, accomplishments, honors and awards, and future plans
Astronautics and aeronautics, 1985: A chronology
This book is part of a series of annual chronologies of significant events in the fields of astronautics and aeronautics. Events covered are international as well as national, in political as well as scientific and technical areas. This series is an important reference work used by historians, NASA personnel, government agencies, and congressional staffs, as well as the media
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