missing error check on MPI call

Allow char* argument to pcfieldsplitsetis_ to be null

Reported-by: Gabel Fabian <gabel.fabian@gmail.com>

Merge branch 'mark/gamg-serial'

start moving GAMGHash to use static inline functions to reduce overhead

very minor cleaning of some GAMG source code

MatDuplicate() for sequential AIJ did not copy over required field
MatDuplicate() does not copy over DM hence things like MatView() fail
Changed PCGAMGFilterGraph() to diagonally scale and use absolu

MatDuplicate() for sequential AIJ did not copy over required field
MatDuplicate() does not copy over DM hence things like MatView() fail
Changed PCGAMGFilterGraph() to diagonally scale and use absolute values of graph matrix even for negative threshold; don't know if this is needed in the algorithm or not

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added an option of negative thresold for generating the graph from the matrix to mean keep even the zero entries in the matrix
This saves all the calls to MatSetValues() for generating the graph matr

added an option of negative thresold for generating the graph from the matrix to mean keep even the zero entries in the matrix
This saves all the calls to MatSetValues() for generating the graph matrix. (MatSetValues calls are known to be slow).

Surprisingly to me it save 20% of the total time on my laptop for one process for
./ex45 -da_refine 4 -pc_type gamg -ksp_monitor -pc_gamg_threshold -1.0 -ksp_type fgmres -ksp_view -log_summary
compared to
./ex45 -da_refine 4 -pc_type gamg -ksp_monitor -pc_gamg_threshold 0.0 -ksp_type fgmres -ksp_view -log_summary
it generated smaller coarse grid matrices and had very similar convergence rate so not only did it essentially eliminate the PCGAMGGraph_AGG time but the other times decreased as well

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added infrastructure for PCView() to provide info on GAMG options and sub GAMG options, such as AGG

removed some unneeded rank and size from gamg code

PetscLogEvent routines do not need to be protected with a #if defined(PETSC_USE_LOG)

unify spelling/abbreviation of some internal GAMG functions and the logging variables and names printed in -log_summary

Please always use the same abbreviations/capitalizations/spellings for related

unify spelling/abbreviation of some internal GAMG functions and the logging variables and names printed in -log_summary

Please always use the same abbreviations/capitalizations/spellings for related things. It is difficult for anyone else to understand/modify code if there are random small differences

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clearer documentation on usage of PCMGGetSmoother()

Reported-by: Yongle Du <yongle.du@gmail.com>

fixed serial gamg bug and cleaned up a bit

PCBDDC: more verbose output for primal indices

Merge branch 'master' into stefano_zampini/pcbddc-adaptive-selection

PCBDDC: added code for loop on rhs instead of computing explicitly the operator

PCBDDC: remove ugly old code for 2D/3D switch

PCBDDC: fix for 64bit indices in PCBDDCSubsetNumbering

PCBDDC: remove unneeded code

Merge branch 'tisaac/feature-gamg-save-perm'

In GAMG, coarse operators can be repartitioned by the createlevel() method: before, the permutation that defines the
repartitioning was not available out

Merge branch 'tisaac/feature-gamg-save-perm'

In GAMG, coarse operators can be repartitioned by the createlevel() method: before, the permutation that defines the
repartitioning was not available outside of the method; now, it can be returned. I added this for situations where
some metadata needs to be passed to the coarse level from the fine level.

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PCBDDC: if rhs is changed, then the starting vector is zero

PCBDDC: silent uninitialized variable warning

PCBDDC: bug fixes for multilevel

hermitian flag is now set to true if the matrix is declared symmetric in real case
This should be handled by PETSc!

PCBDDC; bug fixes

PCBDDC: optimize PCApply_BDDC and PCApplyTranspose_BDDC