arXiv subjects

Enno Diekema

Publications and source records attributed to Enno Diekema.

13 recordsLinked to original sources

arXiv2024

Some integrals which are not in table 129 of Bierens de Haan

In the standard work of Bierens de Haan about integrals we look at table 129. This table lists a number of integrals of a certain kind. In this paper the table is expanded with a number of similar integrals. These are determined by a number of different methods. Some of these methods are not treated in the freshman standard works on integral calculus. As a bonus, we treat an integral using a complete different method which is not so well-known.

math.CA↗

arXiv2024

On the linear (in)dependence of sequences of derivatives of the functions $x^n\sin x$ and $x^n\cos x$

The main goal of the paper is to prove that the sequence of functions $f(x), Df(x), \dots, D^{2n+1}f(x)$, where $f(x)$ is $x^n\sin x$ or $x^n\cos x$ are linearly independent. Or more generally: that the sequence of functions $D^kf(x), D^{k+1}f(x), \dots, D^{2n+k+1}f(x)$, $k\in \mathbb{N}$ is linearly independent. The problem is solved by a suitable transformation of the matrix of determinant of the Wronskian. Another approach for a special sequence of derivatives of functions uses only the definition of linear independence of functions. This approach generates interesting, non-elementary combinatorial identities.

math.GM↗

arXiv2023

Exact formulas for the fourth and fifth cumulant of the Rosenblatt distribution

In an earlier version of this paper \cite{6} a formula for the 4th cumulant of the Rosenblatt distribution was derived. In this paper formulas for the 3rd, 4th and 5th cumulant are derived using two methods. In the first method the necessary integrals are determined directly. The second method is the one used by Veillette and Taqqu. This is a recurring method. Finally both methods are discussed.

math.PR↗

arXiv2022

The Catalan-Qi number of the second kind and a related integral

Li et al. give an integral formula for the Catalan-Qi number of the second kind. They show that this integral can be written as a summation with double factorials. In this paper the integral is reduced to a product of the Catalan number and a hypergeometric function. This hypergeometric function can be written as an associated Legendre polynomial of the first kind. There are also connections with the incomplete Beta function and the Gegenbauer polynomials. In the last section a related integral is calculated.

math.CO↗

arXiv2022

Combinatorial identities and hypergeometric series

This paper describes a method to find a connection between combinatorial identities and hypergeometric series with a number of examples. Combinatorial identities can often be written as hypergeometric series with unit argument. In a number of cases these hypergeometric series are balanced and can be reduced to a simpler form. In this paper some combinatorial identities are proved using this method assuming that the results in the tables of Prudnikov et al. [12] are proven without using hypergeometric functions.

math.CO↗

arXiv2022

Some definite integrals involving Jacobi polynomials

Szmytkowski derived a certain integral with Gegenbauer polynomials. A natural generalization is to derive lookalike integrals with Jacobi polynomials. Six methods are treated to derive the first integral. The first method should be enough to prove the first integral, but by the other methods there arises remarkable formula such as par example a zero-balanced F3 Appell function which can be converted into a 2F1 hypergeometric function. Another three integrals complete the paper.

math.CA↗

arXiv2021

The orthogonal Shmaliy polynomials are Hahn polynomials

Morales-Mendoza et al. present in 2013 a new class of discrete orthogonal polynomials. They use these polynomials to design an unbiased FIR filter. In their paper they make the statement that a representation of the polynomials via hypergeometric functions is unknown. However Shakibaei Asli et al. found in 2017 a $_3F_2$ hypergeometric function representation. In this paper it is shown that the "new" orthogonal polynomials belong to the class of the Hahn polynomials. The transfer function of the unbiased FIR filter has been determined. In the second part, an orthogonal unbiased FIR filter is designed following the method of the orthogonal derivative described in the thesis of the author. In the Appendix a table with a number of possible transformations of the Hahn polynomials is given.

math.CA↗

arXiv2021

An extension of the orthogonal derivative with adjustable precision

The orthogonal derivative is defined as a limit of an integral whose kernel contains an orthogonal polynomial with its measure. When in practice no limit is taken, it means that the accuracy of the derivative depends on the second derivative of the given function. Liptaj shows that it is possible to define a kernel in such a way that the accuracy depends on a higher derivative at your own choice. The accuracy is therefore much greater than with the orthogonal derivative. However Diekema and Koornwinder find a similar extension starting directly from of the orthogonal derivative. The new kernel is not orthogonal for order greater then one. The transfer function for this new derivative is given.

math.CA↗

arXiv2021

Differentiation by integration using orthogonal polynomials, a survey

This survey paper discusses the history of approximation formulas for n-th order derivatives by integrals involving orthogonal polynomials. There is a large but rather disconnected corpus of literature on such formulas. We give some results in greater generality than in the literature. Notably we unify the continuous and discrete case. We make many side remarks, for instance on wavelets, Mantica's Fourier-Bessel functions and Greville's minimum R_alpha formulas in connection with discrete smoothing.

math.CA↗

arXiv2020

The two-dimensional fractional orthogonal derivative

This paper is an edited and shortened version of Chapter 6 from the thesis of the author. First the one dimensional orthogonal derivative will be extended to the two-dimensional case. In the two-dimensional case we have to define the region of integration. In this paper we treat the integration over the square region and over the triangle region where in the last case we use biorthogonal polynomials expressed in terms of Appell functions. Next the two-dimensional orthogonal derivative will be extended to the two-dimensional fractional orthogonal derivative. The results are highly dependent on the $F_1$,\ $F_2$ and $F_3$ Appell functions.

math.CA↗

arXiv2020

A correlation function for the classical orthogonal polynomials

A correlation function of the classical orthogonal polynomials is defined and determined. The correlation function obeys a second order difference equation in two variables. The correlation function for the Gegenbauer, Chebyshev and Legendre polynomials can be written as a 4F3 hypergeometric function. For the Jacobi polynomials the result is an F2 Appell function. For the Generalized Laguerre polynomials the result is a confluent hypergeometric function and for the Hermite polynomials there rests only a single term.

math.CA↗

arXiv2020

Integral representations for Horn's $H_2$ function and Olsson's $F_P$ function

We derive some Euler type double integral representations for hypergeometric functions in two variables. In the first part of this paper we deal with Horn's $H_2$ function, in the second part with Olsson's $F_P$ function. Our double integral representing the $F_P$ function is compared with the formula for the same integral representing an $H_2$ function by M. Yoshida (Hiroshima Math. J. 10 (1980), 329-335 and M. Kita (Japan. J. Math. 18 (1992), 25-74). As specified by Kita, their integral is defined by a homological approach. We present a classical double integral version of Kita's integral, with outer integral over a Pochhammer double loop, which we can evaluate as $H_2$ just as Kita did for his integral. Then we show that shrinking of the double loop yields a sum of two double integrals for $F_P$.

math.CA↗

arXiv2011

Generalizations of an integral for Legendre polynomials by Persson and Strang

Persson and Strang (2003) evaluated the integral over [-1,1] of a squared odd degree Legendre polynomial divided by x^2 as being equal to 2. We consider a similar integral for orthogonal polynomials with respect to a general even orthogonality measure, with Gegenbauer and Hermite polynomials as explicit special cases. Next, after a quadratic transformation, we are led to the general nonsymmetric case, with Jacobi and Laguerre polynomials as explicit special cases. Examples of indefinite summation also occur in this context. The paper concludes with a generalization of the earlier results for Hahn polynomials. There some adaptations have to be made in order to arrive at relatively nice explicit evaluations.

math.CA↗