Hi! I would like to use petsc4py for my own Python library. Installation went well, first tests (serial and parallel) look good.
Here is what I want to do: I have my own time-stepping playground and I want petsc4py to be one of my backbones for the data types and (linear or non-linear, serial or parallel) solvers. I don't want to use PETSc's time-steppers, at least not for now. So, I saw in some examples, in particular the ones shipped with petsc4py, that the standard way of running one of PETSc's solvers is a bunch of setup routines, then setting the right-hand side and solve. Now, I don't want to rerun the whole setup part each time I call the solver. I know that I can change the right-hand side without having to do so, but what if I change a parameter of my operator like, say, the time-step size or some material parameter? Take the simplest case: Say I have my own implicit Euler written in Python. I know the right-hand side F of my ODE, so in each step I want to solve "I - dt*F". But the time-step changes every now and then, so I cannot pre-assemble everything once and for all (or I don't want to). What do I need to rerun before I can use the solver again, what can I reuse? Could I just assemble F and combine it with the identity and the parameter dt right before I call the solver? How would that look like? I'm pretty new to PETSc and to petsc4py, so please forgive any stupidity or ignorance in these questions. I'm happy to take any advice, links to examples or previous questions. Thanks! Kind regards -Robert- -- Dr. Robert Speck Juelich Supercomputing Centre Institute for Advanced Simulation Forschungszentrum Juelich GmbH 52425 Juelich, Germany Tel: +49 2461 61 1644 Fax: +49 2461 61 6656 Email: [email protected] Website: http://www.fz-juelich.de/ias/jsc/speck_r PinT: http://www.fz-juelich.de/ias/jsc/pint ------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------ Forschungszentrum Juelich GmbH 52425 Juelich Sitz der Gesellschaft: Juelich Eingetragen im Handelsregister des Amtsgerichts Dueren Nr. HR B 3498 Vorsitzender des Aufsichtsrats: MinDir Dr. Karl Eugen Huthmacher Geschaeftsfuehrung: Prof. Dr.-Ing. Wolfgang Marquardt (Vorsitzender), Karsten Beneke (stellv. Vorsitzender), Prof. Dr.-Ing. Harald Bolt, Prof. Dr. Sebastian M. Schmidt ------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------
