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Es wird eine Lie-algebraische Verallgemeinerung sowohl des klassischen als auch des Sortier-Jacobi-Verfahrens für das symmetrische Eigenwertproblem behandelt. Der koordinatenfreie Zugang ermöglicht durch eine neue Betrachtungsweise die Vereinheitlichung strukturierter Eigen- und Singulärwertprobleme, darunter bis dato noch nicht betrachtete Fälle. Für beide Verfahren wird lokal quadratische Konvergenz, sowohl für den regulären als auch für den irregulären Fall, gezeigt. Die Analyse und Verallgemeinerung der sog. speziellen Sweeps für das symmetrische Eigenwertproblem führt zu neuen Sweep-Methoden für strukturierte Eigen- und Singulärwertprobleme, die ein besseres Konvergenzverhalten als die bisher bekannten aufweisen. / A Lie algebraic generalization of the classical and the Sort-Jacobi algorithm for diagonalizing a symmetric matrix has been proposed. The coordinate free setting provides new insights in the nature of Jacobi-type methods and allows a unified treatment of several structured eigenvalue and singular value problems, including so far unstudied normal form problems. Local quadratic convergence has been shown for both types of Jacobi methods with a fully comprehension of the regular and irregular case. New sweep methods have been introduced that generalize the special cyclic sweep for symmetric matrices and ensure local quadratic convergence also for irregular elements. The new sweep methods yield faster convergence behavior than the previously known cyclic schemes.

Dans cette Thèse, nous considérons dans le plan complexe l’équation de la chaleur avec la condition initiale singulière u(0,z)=1/(1-exp(z)). Ce problème de Cauchy possède une unique solution formelle série entière, laquelle peut être sommée par des procédés de sommation différents. Le but est d’établir des relations existant entre les différentes sommes ainsi étudiées: d’une part la somme de Borel de celle-ci et, de l’autre, deux versions q-analogues de la somme de Borel qui sont obtenuesrespectivement avec le noyau de la chaleur et la fonction thêta de Jacobi. Notre analyse sur le phénomène de Stokes correspondant nous conduit à une généralisation d’un résultat de Mordell sur le nombre de classes des formes quadratiques binaires définies et positives. / In this thesis, we consider the heat equation with the singular initial condition u(0,z)=1/(1-exp(z)), where z is a complex variable. The aim is to establish relations among three sums of a divergent formal solution to this Cauchy problem: its Borel-sum and two q-Borel-sums obtained by means of heat kernel and theta function respectively. This Stokes analysis allows us to give a generalization to a classical result of Mordell related to the class numbers of the binary positive-definite quadratic forms.

Thesis (M.S.)--University of Missouri, School of Mines and Metallurgy, 1931. / The entire thesis text is included in file. Typescript and handwritten by author. Illustrated by author. Title from title screen of thesis/dissertation PDF file (viewed December 3, 2009) Includes bibliographical references (p. 25) and index (p. 26).

A current group GX is an infinite-dimensional Lie group of smooth maps from a smooth manifold X to a finite-dimensional Lie group G, endowed with pointwise multiplication. This thesis concerns current groups G§ for compact Riemann surfaces §. We extend some results in the literature to discuss the topology of G§ where G has non-trivial fundamental group, and use these results to discuss the theory of central extensions of G§. The second object of interest in the thesis is the Jacobi group, which we think of as being associated to a compact Riemann surface of genus one. A connection is made between the Jacobi group and a certain central extension of G§. Finally, we define a generalisation of the Jacobi group that may be thought of as being associated to a compact Riemann surface of genus g ≥ 1.

Zugl.: Regensburg, Univ., Magisterarbeit, 2004

Thesis (Ph. D.)--University of Missouri-Columbia, 1996. / Typescript. Vita. Includes bibliographical references (leaves 85-88). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1996. / Typescript. Vita. Includes bibliographical references (leaves 85-88). Also available on the Internet.

Thesis (PhD (Mathematics and Applied Mathematics)) -- University of Pretoria, 2007. / Abstract in English. Includes bibliographical references.

Diss. zur erlangung der venia docendi--Jena. / Lebenslauf.