14,491 research outputs found
2HOT: An Improved Parallel Hashed Oct-Tree N-Body Algorithm for Cosmological Simulation
We report on improvements made over the past two decades to our adaptive
treecode N-body method (HOT). A mathematical and computational approach to the
cosmological N-body problem is described, with performance and scalability
measured up to 256k () processors. We present error analysis and
scientific application results from a series of more than ten 69 billion
() particle cosmological simulations, accounting for
floating point operations. These results include the first simulations using
the new constraints on the standard model of cosmology from the Planck
satellite. Our simulations set a new standard for accuracy and scientific
throughput, while meeting or exceeding the computational efficiency of the
latest generation of hybrid TreePM N-body methods.Comment: 12 pages, 8 figures, 77 references; To appear in Proceedings of SC
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Platform independent profiling of a QCD code
The supercomputing platforms available for high performance computing based
research evolve at a great rate. However, this rapid development of novel
technologies requires constant adaptations and optimizations of the existing
codes for each new machine architecture. In such context, minimizing time of
efficiently porting the code on a new platform is of crucial importance. A
possible solution for this common challenge is to use simulations of the
application that can assist in detecting performance bottlenecks. Due to
prohibitive costs of classical cycle-accurate simulators, coarse-grain
simulations are more suitable for large parallel and distributed systems. We
present a procedure of implementing the profiling for openQCD code [1] through
simulation, which will enable the global reduction of the cost of profiling and
optimizing this code commonly used in the lattice QCD community. Our approach
is based on well-known SimGrid simulator [2], which allows for fast and
accurate performance predictions of HPC codes. Additionally, accurate
estimations of the program behavior on some future machines, not yet accessible
to us, are anticipated
The Quantum Mellin transform
We uncover a new type of unitary operation for quantum mechanics on the
half-line which yields a transformation to ``Hyperbolic phase space''. We show
that this new unitary change of basis from the position x on the half line to
the Hyperbolic momentum , transforms the wavefunction via a Mellin
transform on to the critial line . We utilise this new transform
to find quantum wavefunctions whose Hyperbolic momentum representation
approximate a class of higher transcendental functions, and in particular,
approximate the Riemann Zeta function. We finally give possible physical
realisations to perform an indirect measurement of the Hyperbolic momentum of a
quantum system on the half-line.Comment: 23 pages, 6 Figure
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