Calling PCFactorSetMatOrderingType() (or command line option: -pc_factor_mat_ordering_type) to use RCM or 1WD usually helps me a lot. My application is based on highly-unstructured meshes.
Fande, On Thu, Sep 28, 2017 at 2:53 PM, Rachit Prasad <rach...@vt.edu> wrote: > Hi, > > I am trying to solve a highly ill-conditioned matrix and am unable to get > convergence when using ILU(0) or Jacobi and SOR preconditioners. I tried to > implement a higher order ILU by increasing the level of fill-in to 1 by > calling > > call PCFactorSetLevels(pc,1,ierr) > > However, when I do that I get the following memory error: > > [0]PETSC ERROR: --------------------- Error Message > ------------------------------------ > [0]PETSC ERROR: Out of memory. This could be due to allocating > [0]PETSC ERROR: too large an object or bleeding by not properly > [0]PETSC ERROR: destroying unneeded objects. > [0]PETSC ERROR: Memory allocated -2147483648 Memory used by process > -2147483648 > [0]PETSC ERROR: Try running with -malloc_dump or -malloc_log for info. > [0]PETSC ERROR: Memory requested 18446744071863943168! > > While I do understand that increasing the level of fill-in will require > higher memory, the memory requested seems to be way too high. Am I > implementing the higher order ILU correctly? Is there any other subroutine > which I need to call? > > Regards, > Rachit > >
