scholarly journals Generalized Shifted Chebyshev Koornwinder’s Type Polynomials: Basis Transformations

Symmetry ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 692 ◽  
Author(s):  
Mohammad AlQudah ◽  
Maalee AlMheidat
Keyword(s):  
Explicit Formula ◽  
Bernstein Polynomial ◽  
Continuous Functions ◽  
The Other ◽  
Numerical Techniques ◽  
Bernstein Basis ◽  
Fixed Degree ◽  
Explicit Formulas ◽  
Degree Elevation ◽  
Polynomial Bases

Approximating continuous functions by polynomials is vital to scientific computing and numerous numerical techniques. On the other hand, polynomials can be characterized in several ways using different bases, where every form of basis has its advantages and power. By a proper choice of basis, several problems will be removed; for instance, stability and efficiency can be improved, and numerous complications can be resolved. In this paper, we provide an explicit formula of the generalized shifted Chebyshev Koornwinder’s type polynomial of the first kind, T r * ( K 0 , K 1 ) ( x ) , using the Bernstein basis of fixed degree. Moreover, a Bézier’s degree elevation was used to rewrite T r * ( K 0 , K 1 ) ( x ) in terms of a higher degree Bernstein basis without altering the shapes. In addition, explicit formulas of conversion matrices between generalized shifted Chebyshev Koornwinder’s type polynomials and Bernstein polynomial bases were given.

STRONG AND WEAK FORMS OF THE METHOD OF MOMENTS AND THE COUPLED DIPOLE METHOD FOR SCATTERING OF TIME-HARMONIC ELECTROMAGNETIC FIELDS

1992 ◽  
Vol 03 (03) ◽  
pp. 583-603 ◽  
Author(s):  
AKHLESH LAKHTAKIA
Keyword(s):  
Electromagnetic Fields ◽  
Method Of Moments ◽  
Electromagnetic Scattering ◽  
Final Section ◽  
The Other ◽  
Numerical Techniques ◽  
Scattering Problems ◽  
Time Harmonic

Algorithms based on the method of moments (MOM) and the coupled dipole method (CDM) are commonly used to solve electromagnetic scattering problems. In this paper, the strong and the weak forms of both numerical techniques are derived for bianisotropic scatterers. The two techniques are shown to be fully equivalent to each other, thereby defusing claims of superiority often made for the charms of one technique over the other. In the final section, reductions of the algorithms for isotropic dielectric scatterers are explicitly given.

Induced Representations and Invariants

1950 ◽  
Vol 2 ◽  
pp. 334-343 ◽  
Author(s):  
G. DE B. Robinson
Keyword(s):  
Representation Theory ◽  
Symmetric Group ◽  
Explicit Formula ◽  
Linear Group ◽  
Schur Functions ◽  
The Other ◽  
Induced Representations ◽  
Direct Sum ◽  
Invariant Matrices ◽  
The One

1. Introduction. The problem of the expression of an invariant matrix of an invariant matrix as a direct sum of invariant matrices is intimately associated with the representation theory of the full linear group on the one hand and with the representation theory of the symmetric group on the other. In a previous paper the author gave an explicit formula for this reduction in terms of characters of the symmetric group. Later J. A. Todd derived the same formula using Schur functions, i.e. characters of representations of the full linear group.

scholarly journals On Three Constructions of Nanotori

Mathematics ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 2036
Author(s):  
Vesna Andova ◽  
Pavel Dimovski ◽  
Martin Knor ◽  
Riste Škrekovski
Keyword(s):  
Computer Science ◽  
Explicit Form ◽  
Topological Indices ◽  
The Other ◽  
Explicit Formulas ◽  
Extra Parameter

There are three different approaches for constructing nanotori in the literature: one with three parameters suggested by Altshuler, another with four parameters used mostly in chemistry and physics after the discovery of fullerene molecules, and one with three parameters used in interconnecting networks of computer science known under the name generalized honeycomb tori. Altshuler showed that his method gives all non-isomorphic nanotori, but this was not known for the other two constructions. Here, we show that these three approaches are equivalent and give explicit formulas that convert parameters of one construction into the parameters of the other two constructions. As a consequence, we obtain that the other two approaches also construct all nanotori. The four parameters construction is mainly used in chemistry and physics to describe carbon nanotori molecules. Some properties of the nanotori can be predicted from these four parameters. We characterize when two different quadruples define isomorphic nanotori. Even more, we give an explicit form of all isomorphic nanotori (defined with four parameters). As a consequence, infinitely many 4-tuples correspond to each nanotorus; this is due to redundancy of having an “extra” parameter, which is not a case with the other two constructions. This result significantly narrows the realm of search of the molecule with desired properties. The equivalence of these three constructions can be used for evaluating different graph measures as topological indices, etc.

A note on the time-dependent and the stationary behaviour of a semi-infinite reservoir subject to a combination of Markovian inflows

1971 ◽  
Vol 8 (04) ◽  
pp. 708-715 ◽  
Author(s):  
Emlyn H. Lloyd
Keyword(s):  
Functional Equation ◽  
Explicit Formula ◽  
Generating Function ◽  
Present Theory ◽  
The Other ◽  
Time Dependent ◽  
Independent Sequence ◽  
Time Dependent Solution ◽  
Infinite Reservoir ◽  
Stationary Behaviour

The present theory of finite reservoirs is not rich in general theorems even when of the simple Moran type, with unit draft and stationary discrete independent-sequence inflows. For the corresponding systems with unbounded capacity however there are two classes of results which have been known for some time. One of these classes is concerned with the time-dependent solution, where the theory provides a functional equation for the generating function of the time to first emptiness (Kendall (1957)), and the other with the asymptotic stationary distribution of reservoir contents, for which an explicit formula for the generating function is available (Moran (1959)).

scholarly journals A Lemma on Continuous Functions

1960 ◽  
Vol 3 (2) ◽  
pp. 186-187
Author(s):  
J. Lipman
Keyword(s):  
Topological Space ◽  
Fundamental Group ◽  
Closed Interval ◽  
Continuous Functions ◽  
The Other ◽  
Special Consideration ◽  
Boundary Lines

The point of this note is to get a lemma which is useful in treating homotopy between paths in a topological space [1].As explained in the reference, two paths joining a given pair of points in a space E are homotopic if there exists a mapping F: I x I →E (I being the closed interval [0,1] ) which deforms one path continuously into the other. In practice, when two paths are homotopic and the mapping F is constructed, then the verification of all its required properties, with the possible exception of continuity, is trivial. The snag occurs when F is a combination of two or three functions on different subsets of I x I. Then the boundary lines between these subsets have to be given special consideration, and although the problems resulting are routine their disposal can involve some tedious calculation and repetition. In the development [l] of the fundamental group of a space, for example, this sort of situation comes up four or five times.

scholarly journals Discussion of “Accurate and Efficient Explicit Approximations of the Colebrook Flow Friction Equation Based on the Wright ω-Function” by DejanBrkić; and Pavel Praks, Mathematics 2019, 7, 34; doi:10.3390/math7010034

Mathematics ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 253 ◽  
Author(s):  
Lotfi Zeghadnia ◽  
Bachir Achour ◽  
Jean Robert
Keyword(s):  
Friction Factor ◽  
The Other ◽  
Maximum Deviation ◽  
Explicit Formulas ◽  
Flow Friction ◽  
Complex Equation ◽  
Other Hand

The Colebrook-White equation is often used for calculation of the friction factor in turbulent regimes; it has succeeded in attracting a great deal of attention from researchers. The Colebrook–White equation is a complex equation where the computation of the friction factor is not direct, and there is a need for trial-error methods or graphical solutions; on the other hand, several researchers have attempted to alter the Colebrook-White equation by explicit formulas with the hope of achieving zero-percent (0%) maximum deviation, among them Dejan Brkić and Pavel Praks. The goal of this paper is to discuss the results proposed by the authors in their paper:” Accurate and Efficient Explicit Approximations of the Colebrook Flow Friction Equation Based on the Wright ω-Function” and to propose more accurate formulas.

Jacobi-Bernstein Basis Transformation

2004 ◽  
Vol 4 (2) ◽  
pp. 206-214 ◽  
Author(s):  
Abedallah Rababah
Keyword(s):  
Least Squares ◽  
Jacobi Polynomial ◽  
Bernstein Polynomial ◽  
Jacobi Polynomials ◽  
Polynomial Basis ◽  
Bernstein Basis ◽  
Bezier Curves ◽  
Bézier Curves ◽  
The Matrix ◽  
Bernstein Polynomial Basis

Abstract In this paper we derive the matrix of transformation of the Jacobi polynomial basis form into the Bernstein polynomial basis of the same degree n and vice versa. This enables us to combine the superior least-squares performance of the Jacobi polynomials with the geometrical insight of the Bernstein form. Application to the inversion of the Bézier curves is given.

scholarly journals Approximations of continuous functions by squares

1990 ◽  
Vol 10 (2) ◽  
pp. 361-366
Author(s):  
Paul D. Humke ◽  
Miklós Laczkovich
Keyword(s):  
Continuous Function ◽  
Borel Subset ◽  
Continuous Functions ◽  
Geometric Characterization ◽  
The Other ◽  
Proper Subset ◽  
Space Of Continuous Functions ◽  
Other Hand ◽  
Decreasing Functions ◽  
Function Mapping

AbstractLet C denote the space of continuous functions mapping [0,1] into itself and endowed with the sup metric. It has been shown that C2 = {f ∘ f: ∈ C} is an analytic but non-Borel subset of C. This implies that there is no simple geometric characterization for a function being a square. In this paper we consider the problem of characterizing those functions which can be approximated by squares. In the first section we prove that any continuous function mapping a closed proper subset of [0,1 ] into [0,1 ] can be extended to a square. In particular this shows that C2 is Lp dense in C. On the other hand, C2 does not contain a ball when C is endowed with the sup metric. In the second section we prove that no strictly decreasing function can be uniformly approximated by squares, although the distance between the class of strictly decreasing functions and C2 is zero. In the last section we investigate the function f(x) = 1 − x and show that for every g ∈ C and that ¼ cannot be improved.

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