Numerical integration of multibody systems by a projection technique

SIGLEAvailable from TIB Hannover: RN7879(9201) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

STABCOL: an efficient implementation of the Weisfeiler-Leman algorithm

A coherent algebra is a matrix algebra over the field of the complex numbers which is closed under conjugate transposition and elementwise multiplication of matrices and which contains the identity matrix and the all 1 matrix. This algebraic structure has a variety of important applications. Among others, coherent algebras are an appropriate tool in the design of algorithms for two notoriously hard graph theoretical problems: the problems of deciding whether two graphs are isomorphic and of finding the automorphism partition of a graph. Weisfeiler and Leman stated a polynomial algorithm which computes the coherent algebra which is generated by the adjacency matrix of a graph. However, for almost three decades, no reasonable time bound was known for this method. Very recently, one of the authors established a theoretical time bound of O(n"3 log n) with n denoting the number of vertices in the graph. The aim of this paper is to document a computer implementation of the algorithm of Weisfeiler-Leman with the above-mentioned complexity. The program is called STABCOL and is coded in programming language C. We give a detailed description as well as a program listing and instructions how to use the program. (orig.)SIGLEAvailable from TIB Hannover: RN 7879(9611) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Intrinsic clock as a tool for path integration An example

SIGLECopy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Intrinsic clock as a tool for path integration An example

SIGLECopy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Element-oriented and edge-oriented local error estimators for nonconforming finite element methods

SIGLEAvailable from TIB Hannover: RN7879(9206) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Element-oriented and edge-oriented local error estimators for nonconforming finite element methods

SIGLEAvailable from TIB Hannover: RN7879(9206) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

STABCOL: an efficient implementation of the Weisfeiler-Leman algorithm

A coherent algebra is a matrix algebra over the field of the complex numbers which is closed under conjugate transposition and elementwise multiplication of matrices and which contains the identity matrix and the all 1 matrix. This algebraic structure has a variety of important applications. Among others, coherent algebras are an appropriate tool in the design of algorithms for two notoriously hard graph theoretical problems: the problems of deciding whether two graphs are isomorphic and of finding the automorphism partition of a graph. Weisfeiler and Leman stated a polynomial algorithm which computes the coherent algebra which is generated by the adjacency matrix of a graph. However, for almost three decades, no reasonable time bound was known for this method. Very recently, one of the authors established a theoretical time bound of O(n"3 log n) with n denoting the number of vertices in the graph. The aim of this paper is to document a computer implementation of the algorithm of Weisfeiler-Leman with the above-mentioned complexity. The program is called STABCOL and is coded in programming language C. We give a detailed description as well as a program listing and instructions how to use the program. (orig.)SIGLEAvailable from TIB Hannover: RN 7879(9611) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

A multiple shooting approach for the numerical treatment of stellar structure and evolution

We present a new numerical method for solving the system of partial differential equations describing the structure and evolution of a spherically symmetric star. As usual, we employ the transversal method of lines in order to split the equations into a coupled spatial and temporal part. The novel features of the algorithm are the following: (a) Instead of using the Lagrangian picture we formulate the system of partial differential equations in the Eulerian picture. (b) We reformulate the equations of stellar structure as a multipoint boundary-value problem. By means of this reformulation the rather clumsy iterative matching procedure of stellar atmosphere and interior is avoided. (c) The multipoint boundary-value problem is solved by the multiple shooting method. This approach not only ensures a high accuracy of the stellar models calculated at each time step but also allows the free boundaries inside the star due to different energy transport mechanisms to be located exactly. (d) The time derivatives involved in the stellar-structure equations are discretized implicitly to second order accuracy. Moreover, at each time step, the chemical abundances are determined by using a sophisticated update procedure. In this way, a high accuracy is achieved with respect to the integration in time. (orig.)SIGLEAvailable from TIB Hannover: RO 7722(447) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDeutsche Forschungsgemeinschaft (DFG), Bonn (Germany)DEGerman

Packing under tolerance constraints (preliminary version)

Available from TIB Hannover: RN 7879(9619) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDeutsche Forschungsgemeinschaft (DFG), Bonn (Germany)DEGerman

System and environment: The Philosophers revisited

SIGLETIB: RN 7878(9040) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman