Proefschrift--Leyden. / Includes bibliographical references.

Proefschrift--Leyden. / Includes bibliographical references.

The main problem considered is the effect due to changes in the shape of the region on the convergence rate of the Gauss-Seidel iterative method for solving the Dirichlet Difference Problem. Experimentally, it is found that as a rule the number of iterations required to attain convergence decreases as the perimeter of the region is increased. The ensuing theoretical investigation leads to the examination of the corresponding iteration matrices and a qualitative theory results which predicts that the number of iterations should increase with the number of nonzero off - diagonal elements in the matrix of the linear system. Further experiments indicate that the latter relationship is no more precise than the former; the lack of rigour in the theory is undoubtedly to blame. Better results, are obtained in the sub-problem of estimating the number of iterations necessary to satisfy a suitable convergence criterion, given a good estimate of the spectral radius of the iteration matrix corresponding to the region under study. / Science, Faculty of / Mathematics, Department of / Graduate

We consider the entire function [formula omitted] whose set of zeros includes the zeros of [formula omitted](s), expand it in an everywhere converging Maclauring series [formula omitted] Then we determine analytic expressions for the coefficients a[formula omitted] which will enable us to proceed with the numerical evaluation of some of these coefficients. To achieve this, we define an operator D[formula omitted] acting on a restricted class of power series and which we call the zeta operator. Using the operator D[formula omitted], we are able to express the coefficients a[formula omitted] as infinite n-dimensional integrals. Numerical values for the coefficients a₀ and a₁ are easily determined. For a₂ and a₃, we transform the multidimensional integrals into products of single integrals and obtain infinite series expressions for these coefficients. Although our method can also be used on the following coefficients, it turns out that the work involved to obtain an expression leading to a practical numerical evaluation of a₄, a₅, …,seems prohibitive at this stage. We then proceed with the numerical computation of a₂ and a₃ and we use these coefficients to calculate the sums of reciprocals of the zeros of [formula omitted](s) in the critical strip. Finally, assuming Riemann hypothesis, we calculate a few other quantities which may prove to be of interest. / Science, Faculty of / Computer Science, Department of / Graduate

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<p>In this paper I give a description and derivation of Dirichlet's problem, a boundary value problem, for p-harmonic functions on graphs and study an iterative method for solving it.The method's convergence is proved and some preliminary results about its speed of convergence are presented.There is an implementation accompanying this thesis and a short description of the implementation is included. The implementation will be made available on the internet at http://www.mai.liu.se/~anbjo/pharmgraph/ for as long as possible.</p>

In this paper I give a description and derivation of Dirichlet's problem, a boundary value problem, for p-harmonic functions on graphs and study an iterative method for solving it.The method's convergence is proved and some preliminary results about its speed of convergence are presented.There is an implementation accompanying this thesis and a short description of the implementation is included. The implementation will be made available on the internet at http://www.mai.liu.se/~anbjo/pharmgraph/ for as long as possible.

Ce mémoire s'emploie à étudier les corps quadratiques réels ainsi qu'un élément particulier de tels corps quadratiques réels : l'unité fondamentale. Pour ce faire, le mémoire commence par présenter le plus clairement possible les connaissances sur différents sujets qui sont essentiels à la compréhension des calculs et des résultats de ma recherche. On introduit d'abord les corps quadratiques ainsi que l'anneau de ses entiers algébriques et on décrit ses unités. On parle ensuite des fractions continues puisqu'elles se retrouvent dans un algorithme de calcul de l'unité fondamentale. On traite ensuite des formes binaires quadratiques et de la formule du nombre de classes de Dirichlet, laquelle fait intervenir l'unité fondamentale en fonction d'autres variables. Une fois cette tâche accomplie, on présente nos calculs et nos résultats. Notre recherche concerne la répartition des unités fondamentales des corps quadratiques réels, la répartition des unités des corps quadratiques réels et les moments du logarithme de l'unité fondamentale. (Le logarithme de l'unité fondamentale est appelé le régulateur.) / This memoir aims to study real quadratic fields and a particular element of such real quadratic fields : the fundamental unit. To achieve this, the memoir begins by presenting as clearly as possible the state of knowledge on different subjects that are essential to understand the computations and results of my research. We first introduce quadratic fields and their rings of algebraic integers, and we describe their units. We then talk about continued fractions because they are present in an algorithm to compute the fundamental unit. Afterwards, we proceed with binary quadratic forms and Dirichlet's class number formula, which involves the fundamental unit as a function of other variables. Once the above tasks are done, we present our calculations and results. Our research concerns the distribution of fundamental units in real quadratic fields, the disbribution of units in real quadratic fields and the moments of the logarithm of the fundamental unit. (The logarithm of the fundamental unit is called the regulator.)

Ce mémoire s'emploie à étudier les corps quadratiques réels ainsi qu'un élément particulier de tels corps quadratiques réels : l'unité fondamentale. Pour ce faire, le mémoire commence par présenter le plus clairement possible les connaissances sur différents sujets qui sont essentiels à la compréhension des calculs et des résultats de ma recherche. On introduit d'abord les corps quadratiques ainsi que l'anneau de ses entiers algébriques et on décrit ses unités. On parle ensuite des fractions continues puisqu'elles se retrouvent dans un algorithme de calcul de l'unité fondamentale. On traite ensuite des formes binaires quadratiques et de la formule du nombre de classes de Dirichlet, laquelle fait intervenir l'unité fondamentale en fonction d'autres variables. Une fois cette tâche accomplie, on présente nos calculs et nos résultats. Notre recherche concerne la répartition des unités fondamentales des corps quadratiques réels, la répartition des unités des corps quadratiques réels et les moments du logarithme de l'unité fondamentale. (Le logarithme de l'unité fondamentale est appelé le régulateur.) / This memoir aims to study real quadratic fields and a particular element of such real quadratic fields : the fundamental unit. To achieve this, the memoir begins by presenting as clearly as possible the state of knowledge on different subjects that are essential to understand the computations and results of my research. We first introduce quadratic fields and their rings of algebraic integers, and we describe their units. We then talk about continued fractions because they are present in an algorithm to compute the fundamental unit. Afterwards, we proceed with binary quadratic forms and Dirichlet's class number formula, which involves the fundamental unit as a function of other variables. Once the above tasks are done, we present our calculations and results. Our research concerns the distribution of fundamental units in real quadratic fields, the disbribution of units in real quadratic fields and the moments of the logarithm of the fundamental unit. (The logarithm of the fundamental unit is called the regulator.)