[petsc-users] fieldsplit error

[Hong Zhang]

subramanya:

>  Hi,
> I figured out that block size was missing. However I am not quite sure
> what the block size means.
>

number of fields.
See
 ./ex19 -snes_monitor_short -ksp_monitor_short -pc_type fieldsplit
-pc_fieldsplit_block_size 2 -pc_fieldsplit_0_fields 0,1
-pc_fieldsplit_1_fields 0,1 -pc_fieldsplit_type multiplicative -snes_view
-fieldsplit_pc_type lu -da_refine 1 -ksp_type fgmres -h |grep
fieldsplit_block_size
  -pc_fieldsplit_block_size <-1>: Blocksize that defines number of fields
(PCFieldSplitSetBlockSize)

Hong

>
> --- Original Message ---
>
> From: "Hong Zhang" <hzhang at mcs.anl.gov>
> Sent: December 28, 2013 12:06 AM
> To: "subramanya sadasiva" <potaman at outlook.com>
> Cc: petsc-users at mcs.anl.gov, libmesh-users at lists.sourceforge.net
> Subject: Re: [petsc-users] fieldsplit error
>
>  Add
> -pc_fieldsplit_block_size 2
>
>  See example
> petsc/src/snes/examples/tutorials/ex19.c:
> ./ex19 -snes_monitor_short -ksp_monitor_short -pc_type fieldsplit
> -pc_fieldsplit_block_size 2 -pc_fieldsplit_0_fields 0,1
> -pc_fieldsplit_1_fields 0,1 -pc_fieldsplit_type multiplicative -snes_view
> -fieldsplit_pc_type lu -da_refine 1 -ksp_type fgmres
>
>  (see runex19_8 in petsc/src/snes/examples/tutorials/makefile)
>
>  Hong
>
>
> On Fri, Dec 27, 2013 at 9:25 PM, subramanya sadasiva <potaman at outlook.com>wrote:
>
>  Hi,
> I have a nonlinear system with 6 variables grouped in two sets of 3. I am
> trying to get a fieldsplit preconditioner working . I have the following
> options set up
>
>  -pc_type fieldsplit
> -pc_fieldsplit_type multiplicative
> -fieldsplit_0_fields 0,2,4
> -fieldsplit_1_fields 1,3,5
> -fieldsplit_0_ksp cg
> -fieldsplit_1_ksp cg
> -fieldsplit_0_pc hypre
> -fieldsplit_1_pc hypre
>
>  However, I get the following error. My installation of libmesh has block
> matrices disabled, which I've seen to cause problems with fieldsplit. Any
> ideas what might cause this error?
> Thanks,
> Subramanya
>
>
>
>  [0]PETSC ERROR: --------------------- Error Message
> ------------------------------------
> [0]PETSC ERROR: Petsc has generated inconsistent data!
> [0]PETSC ERROR: Unhandled case, must have at least two fields, not 1!
> [0]PETSC ERROR:
> ------------------------------------------------------------------------
> [0]PETSC ERROR: Petsc Release Version 3.4.3, unknown
> [0]PETSC ERROR: See docs/changes/index.html for recent updates.
> [0]PETSC ERROR: See docs/faq.html for hints about trouble shooting.
> [0]PETSC ERROR: See docs/index.html for manual pages.
>
>
>
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