Results 71 to 80 of about 574,412 (205)

Measuring the Phase of an Optical Field from Two Intensity Measurements: Analysis of a Simple Theoretical Model

International Journal of Optics, 2018
Under the scalar paraxial approximation, an optical wavefield is considered to be complex function dependent on position; i.e., at a given location in space the optical field is a complex value with an intensity and phase.
Damien P. Kelly
doaj   +1 more source

New Bernstein type inequalities for polynomials on ellipses [PDF]

New and sharp estimates are derived for the growth in the complex plane of polynomials known to have a curved majorant on a given ellipse. These so-called Bernstein type inequalities are closely connected with certain constrained Chebyshev approximation ...
Fischer, Bernd, Freund, Roland
core   +1 more source

Dynamical response of a one dimensional quantum wire electron system

, 1996
We provide a self-contained theoretical analysis of the dynamical response of a one dimensional electron system, as confined in a semiconductor quantum wire, within the random phase approximation. We carry out a detailed comparison with the corresponding
Hwang, E. H., Sarma, S. Das
core   +1 more source

Optimal Chebyshev polynomials on ellipses in the complex plane [PDF]

The design of iterative schemes for sparse matrix computations often leads to constrained polynomial approximation problems on sets in the complex plane.
Fischer, Bernd, Freund, Roland
core   +1 more source

Fast and stable contour integration for high order divided differences via elliptic functions [PDF]

, 2015
In this paper, we will present a new method for evaluating high order divided differences for certain classes of analytic, possibly, operator valued functions.
LOPEZ FERNANDEZ, Maria, S, Sauter
core  

Calculating resonance positions and widths using the Siegert approximation method

, 2011
Here we present complex resonance states (or Siegert states), that describe the tunneling decay of a trapped quantum particle, from an intuitive point of view which naturally leads to the easily applicable Siegert approximation method that can be used ...
Glück M, Kevin Rapedius, Messiah A, Moiseyev N, Rapedius K, Taylor J R   +5 more
core   +2 more sources

Approximation of classes of Poisson integrals by rectangular Fejér means

Frontiers in Applied Mathematics and Statistics
The article is devoted to the problem of approximation of classes of periodic functions by rectangular linear means of Fourier series. Asymptotic equalities are found for upper bounds of deviations in the uniform metric of rectangular Fejér means on ...
Olga Rovenska
doaj   +1 more source

Deterministic polynomial-time approximation algorithms for partition functions and graph polynomials

, 2017
In this paper we show a new way of constructing deterministic polynomial-time approximation algorithms for computing complex-valued evaluations of a large class of graph polynomials on bounded degree graphs.
Patel, Viresh, Regts, Guus
core   +2 more sources

Accuracy Examination of the Fourier Series Approximation for Almost Limiting Gravity Waves on Deep Water

Mathematical and Computational Applications
A permanent gravity wave propagating on deep water is a classic mathematical problem. However, the Fourier series approximation (FSA) based on the physical plane was examined to be valid for almost waves at all depths.
Yang-Yih Chen, Hsien-Kuo Chang
doaj   +1 more source

On the condition number of some gram matrices arising from least squares approximation in the complex plane [PDF]

Numerische Mathematik, 1986
This paper is concerned with the condition numbers of Gram matrices that arise when computing least square polynomials in polygons of the complex plane. For a stability reason, instead of the power basis \(\{1,\lambda,\lambda^ 2,...,\lambda^ n\}\), polynomials are expressed on the basis of Chebyshev polynomials of the first kind.
openaire   +2 more sources