ieee754的標準，原英文版的！Twenty years ago anarchy threatened floating-point arithmetic. Over a dozen commercially significant arithmetics
boasted diverse wordsizes, precisions, rounding procedures and over/underflow behaviors, and more were in the
works. “Portable” software intended to reconcile that numerical diversity had become unbearably costly to
develop.
Thirteen years ago, when IEEE 754 became official, major microprocessor manufacturers had already adopted it
despite the challenge it posed to implementors. With unprecedented altruism, hardware designers had risen to its
challenge in the belief that they would ease and encourage a vast burgeoning of numerical software. They did
succeed to a considerable extent. Anyway, rounding anomalies that preoccupied all of us in the 1970s afflict only
CRAY X-MPs — J90s now.
TPMath is a library of scientific programs written in Pascal. Available in several versions according to the compiler, it is proposed as an alternative to the famous Numerical Recipes, for which the Pascal version is no longer developed, or to the Borland Numerical Methods Toolbox which is no longer available.
We introduce a sub-cell WENO reconstruction method to evaluate spatial derivatives in the high-order ADER scheme. The basic idea in our reconstruction is to use only r stencils to reconstruct the point-wise values of solutions and spatial derivatives for the 2r-1 th order
ADER scheme in one dimension, while in two dimensions, the dimension-by-dimension sub-cell reconstruction approach for spatial derivatives is employed. Compared with the original ADER scheme of Toro and Titarev (2002) [2] that uses the direct derivatives of reconstructed polynomials for solutions to evaluate spatial derivatives, our method not only reduces greatly the computational costs of the ADER scheme on a given mesh,
but also avoids possible numerical oscillations near discontinuities, as demonstrated by a number of one- and two-dimensional numerical tests. All these tests show that the 5th-order ADER scheme based on our sub-cell reconstruction method achieves the desired accuracy, and is essentially non-oscillatory and computationally cheaper for problems with discontinuities.
We show in the context of a new economic geography model that when
labor is heterogenous trade liberalization may lead to industrial agglomeration
and inter-regional trade. Labor heterogeneity gives local monopoly
power to firms but also introduces variations in the quality of the job match.
Matches are likely to be better when there are more firms and workers in
the local market, giving rise to an agglomeration force which can offset the
forces against, trade costs and the erosion of monopoly power. We derive
analytically a robust agglomeration equilibrium and illustrate its properties
with numerical simulations
Improved guaranteed cost control and quantum adaptive control are developed in this study for a quadrotor helicopter with state
delay and actuator faults. Improved guaranteed cost control is designed to eliminate disturbance effects and guarantee the robust stability of a
quadrotor helicopter with state delay. The inapplicability of guaranteed cost control to the quadrotor linear model is addressed by combining
guaranteed cost control with a model reference linear quadratic regulator. In the event of actuator faults, quadrotor tracking performance is
maintained through quantum adaptive control. Finally, the availability of the proposed scheme is verified through numerical simulation
The recent developments in full duplex (FD) commu-
nication promise doubling the capacity of cellular networks using
self interference cancellation (SIC) techniques. FD small cells
with device-to-device (D2D) communication links could achieve
the expected capacity of the future cellular networks (5G). In
this work, we consider joint scheduling and dynamic power
algorithm (DPA) for a single cell FD small cell network with
D2D links (D2DLs). We formulate the optimal user selection and
power control as a non-linear programming (NLP) optimization
problem to get the optimal user scheduling and transmission
power in a given TTI. Our numerical results show that using
DPA gives better overall throughput performance than full power
transmission algorithm (FPA). Also, simultaneous transmissions
(combination of uplink (UL), downlink (DL), and D2D occur
80% of the time thereby increasing the spectral efficiency and
network capacity
Theartofcomputationofelectromagnetic(EM)problemshasgrownexponentially
for three decades due to the availability of powerful computer resources. In spite of
this, the EM community has suffered without a suitable text on the computational
techniques commonly used in solving EM-related problems. Although there have
been monographs on one particular technique or another, the monographs are written
for the experts rather than students. Only a few texts cover the major techniques and
dothatinamannersuitableforclassroomuse.Itseemsexpertsinthisareaarefamiliar
with one or a few techniques but not many seem to be familiar with all the common
techniques. This text attempts to fill that gap.
InGaAs/AlGaAs semiconductor lasers come in threetypes: VCSELs and two types of EELs. The VCSEL, asits name implies, emits vertically, normal to the planeof the device, owing to cavity mirrors grown withinthe epitaxial material itself. The VCSEL’s circular beamhas a numerical aperture (NA) of roughly 0.2, or a fullangle of approximately 25 degrees.
