[petsc-users] How to use multigrid?

[w_ang_temp]

>At 2012-11-04 01:08:26,"Jed Brown" <jedbrown at mcs.anl.gov> wrote:


>1. What kind of equation are you solving? AMG is not working well if it takes that many iterations.


I just deal with the typical soil-water coupled geotechnical problems. It is a typical finite element equation. The matrix is 30000X30000 and ill-conditioned.

 


2.



      ##########################################################
      #                                                        #
      #                          WARNING!!!                    #
      #                                                        #
      #   This code was compiled with a debugging option,      #
      #   To get timing results run ./configure                #
      #   using --with-debugging=no, the performance will      #
      #   be generally two or three times faster.              #
      #                                                        #
      ##########################################################
It is true a debugging version. And I used the same version dealing with the same problem, one preconditioner is asm
and the other is amg. The time with amg is about 3 times as with asm. I do not know the reason. And I also do not know the
meaning of '[0]PCSetData_AGG bs=1 MM=7601'.

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