TY - CHAP A1 - Nowak, Ulrich A1 - Pöhle, Uwe A1 - Roitzsch, Rainer ED - Mackens, W. ED - Rump, S. T1 - Eine graphische Oberfläche für numerische Programme T2 - Software Engineering im Scientific Computing Y1 - 1996 SP - 264 EP - 278 PB - Vieweg ER - TY - CHAP A1 - Nowak, Ulrich A1 - Pöhle, Uwe A1 - Roitzsch, Rainer A1 - Sukrow, B. ED - Mackens, W. ED - Rump, S. T1 - Formale Spezifikation des ZIB-GUI mit Hilfe von Graph-Grammatiken T2 - Software Engineering im Scientific Computing Y1 - 1996 SP - 290 EP - 296 PB - Vieweg ER - TY - GEN A1 - Lubich, Christian A1 - Nowak, Ulrich A1 - Pöhle, Uwe A1 - Engstler, Ch. T1 - MEXX - Numerical Software for the Integration of Constrained Mechanical Systems. N2 - MEXX (short for MEXanical systems eXtrapolation integrator) is a Fortran code for time integration of constrained mechanical systems. MEXX is suited for direct integration of the equations of motion in descriptor form. It is based on extrapolation of a time stepping method that is explicit in the differential equations and linearly implicit in the nonlinear constraints. It only requires the solution of well--structured systems of linear equations which can be solved with a computational work growing linearly with the number of bodies, in the case of multibody systems with few closed kinematic loops. Position and velocity constraints are enforced throughout the integration interval, whereas acceleration constraints need not be formulated. MEXX has options for time--continuous solution representation (useful for graphics) and for the location of events such as impacts. The present article describes MEXX and its underlying concepts. T3 - ZIB-Report - SC-92-12 Y1 - 1992 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-823 ER -