On 6 April 2018 at 08:48, Robert Speck <[email protected]> wrote: > Thank you for your answer! Please see below for comments/questions. > > On 05.04.18 12:53, Matthew Knepley wrote: >> On Thu, Apr 5, 2018 at 6:39 AM, Robert Speck <[email protected]
>> >> For nonlinear solves which stay the same size, you do nothing. > > "nothing" in terms of "nothing you can do" or "nothing you have to do"? > I would say "nothing you have to do". Nonlinear solvers work by just setting two callback routines to compute the residual and the Jacobian. The user-defined residual routine receives a vector you have to put values in, same for the Jacobian routine, you have to put values in the (already preallocated) matrix that is reused on each newton step, and on each successive solve. SNES will take care of everything else (in particular, updating the KSP linear solver, and refreshing the preconditioner, always trying to reuse already-preallocated internal data structures as much as possible). All what what I said for SNES applies to TS, in case you ever want to give it a chance. -- Lisandro Dalcin ============ Research Scientist Computer, Electrical and Mathematical Sciences & Engineering (CEMSE) Extreme Computing Research Center (ECRC) King Abdullah University of Science and Technology (KAUST) http://ecrc.kaust.edu.sa/ 4700 King Abdullah University of Science and Technology al-Khawarizmi Bldg (Bldg 1), Office # 0109 Thuwal 23955-6900, Kingdom of Saudi Arabia http://www.kaust.edu.sa Office Phone: +966 12 808-0459
