4,779 research outputs found
Parallel software for lattice N=4 supersymmetric Yang--Mills theory
We present new parallel software, SUSY LATTICE, for lattice studies of
four-dimensional supersymmetric Yang--Mills theory with gauge
group SU(N). The lattice action is constructed to exactly preserve a single
supersymmetry charge at non-zero lattice spacing, up to additional potential
terms included to stabilize numerical simulations. The software evolved from
the MILC code for lattice QCD, and retains a similar large-scale framework
despite the different target theory. Many routines are adapted from an existing
serial code, which SUSY LATTICE supersedes. This paper provides an overview of
the new parallel software, summarizing the lattice system, describing the
applications that are currently provided and explaining their basic workflow
for non-experts in lattice gauge theory. We discuss the parallel performance of
the code, and highlight some notable aspects of the documentation for those
interested in contributing to its future development.Comment: Code available at https://github.com/daschaich/sus
Chaste: a test-driven approach to software development for biological modelling
Chaste (âCancer, heart and soft-tissue environmentâ) is a software library and a set of test suites for computational simulations in the domain of biology. Current functionality has arisen from modelling in the fields of cancer, cardiac physiology and soft-tissue mechanics. It is released under the LGPL 2.1 licence.\ud
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Chaste has been developed using agile programming methods. The project began in 2005 when it was reasoned that the modelling of a variety of physiological phenomena required both a generic mathematical modelling framework, and a generic computational/simulation framework. The Chaste project evolved from the Integrative Biology (IB) e-Science Project, an inter-institutional project aimed at developing a suitable IT infrastructure to support physiome-level computational modelling, with a primary focus on cardiac and cancer modelling
Quantitative Analysis of Probabilistic Models of Software Product Lines with Statistical Model Checking
We investigate the suitability of statistical model checking techniques for
analysing quantitative properties of software product line models with
probabilistic aspects. For this purpose, we enrich the feature-oriented
language FLan with action rates, which specify the likelihood of exhibiting
particular behaviour or of installing features at a specific moment or in a
specific order. The enriched language (called PFLan) allows us to specify
models of software product lines with probabilistic configurations and
behaviour, e.g. by considering a PFLan semantics based on discrete-time Markov
chains. The Maude implementation of PFLan is combined with the distributed
statistical model checker MultiVeStA to perform quantitative analyses of a
simple product line case study. The presented analyses include the likelihood
of certain behaviour of interest (e.g. product malfunctioning) and the expected
average cost of products.Comment: In Proceedings FMSPLE 2015, arXiv:1504.0301
GHOST: Building blocks for high performance sparse linear algebra on heterogeneous systems
While many of the architectural details of future exascale-class high
performance computer systems are still a matter of intense research, there
appears to be a general consensus that they will be strongly heterogeneous,
featuring "standard" as well as "accelerated" resources. Today, such resources
are available as multicore processors, graphics processing units (GPUs), and
other accelerators such as the Intel Xeon Phi. Any software infrastructure that
claims usefulness for such environments must be able to meet their inherent
challenges: massive multi-level parallelism, topology, asynchronicity, and
abstraction. The "General, Hybrid, and Optimized Sparse Toolkit" (GHOST) is a
collection of building blocks that targets algorithms dealing with sparse
matrix representations on current and future large-scale systems. It implements
the "MPI+X" paradigm, has a pure C interface, and provides hybrid-parallel
numerical kernels, intelligent resource management, and truly heterogeneous
parallelism for multicore CPUs, Nvidia GPUs, and the Intel Xeon Phi. We
describe the details of its design with respect to the challenges posed by
modern heterogeneous supercomputers and recent algorithmic developments.
Implementation details which are indispensable for achieving high efficiency
are pointed out and their necessity is justified by performance measurements or
predictions based on performance models. The library code and several
applications are available as open source. We also provide instructions on how
to make use of GHOST in existing software packages, together with a case study
which demonstrates the applicability and performance of GHOST as a component
within a larger software stack.Comment: 32 pages, 11 figure
Towards the Formal Specification and Verification of Maple Programs
In this paper, we present our ongoing work and initial results on the formal
specification and verification of MiniMaple (a substantial subset of Maple with
slight extensions) programs. The main goal of our work is to find behavioral
errors in such programs w.r.t. their specifications by static analysis. This
task is more complex for widely used computer algebra languages like Maple as
these are fundamentally different from classical languages: they support
non-standard types of objects such as symbols, unevaluated expressions and
polynomials and require abstract computer algebraic concepts and objects such
as rings and orderings etc. As a starting point we have defined and formalized
a syntax, semantics, type system and specification language for MiniMaple
Orbifold equivalence: structure and new examples
Orbifold equivalence is a notion of symmetry that does not rely on group
actions. Among other applications, it leads to surprising connections between
hitherto unrelated singularities. While the concept can be defined in a very
general category-theoretic language, we focus on the most explicit setting in
terms of matrix factorisations, where orbifold equivalences arise from defects
with special properties. Examples are relatively difficult to construct, but we
uncover some structural features that distinguish orbifold equivalences -- most
notably a finite perturbation expansion. We use those properties to devise a
search algorithm, then present some new examples including Arnold
singularities.Comment: 34 pages, web-link to Singular code provide
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