[petsc-users] question about small matrices

Dear Petsc developers, in my application I have to solve millions of linear and non-linear systems with small matrices (2x2, 3x3,..., 10x10). I consider them as dense, and use SNES with KSP method PREONLY, and LU preconditioner. I found that when KSPSolve is called only 25% of time is spend

Re: [petsc-users] TS scheme with different DAs

Hello all, I finally implemented the TS routine operating in several DAs at the same time, hacking it as you suggested. I still have a problem with my algorithm though. It is not DMDA related so there's that. My algorithm needs to update u,v,w with information from the updated T,S,rho. My

[petsc-users] Problem about Scaling

Respected Petsc developers Hi, I am currently using SNES to solve some non-linear PDEs. The model is a two-dimensional X-Y geometry. Because the magnitude of different physical variables is too large, it is difficult to find the direction in Krylov subspace, and the residual descends very slowly

[petsc-users] R: Multiple linear solver defined at command line

Thank you, Lawrence. Cool! That's perfect! Bests, Marco Cisternino Da: Lawrence Mitchell Inviato: martedì 24 settembre 2019 13:59 A: Marco Cisternino Cc: petsc-users Oggetto: Re: [petsc-users] Multiple linear solver defined at command line Dear Marco,

[petsc-users] Multiple linear solver defined at command line

Good morning, in my code I need to solve 2 linear systems. I would like to use different solvers for the 2 systems and most of all I would like to choose the single solver by flags from command line, is it possible? I can call PetscInitialize/PetscFinalize multiple times passing PetscInitialize