PETSc version 3.15.5
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# PCTFS

A parallel direct solver intended for problems with very few unknowns (like the coarse grid in multigrid). Performs a Cholesky or LU factorization of a matrix defined by its local matrix vector product. Implemented by Henry M. Tufo III and Paul Fischer originally for Nek5000 and called XXT or XYT

### Notes

Only implemented for the MPIAIJ matrices

Only works on a solver object that lives on all of PETSC_COMM_WORLD!

Only works for real numbers (is not built if PetscScalar is complex)

### See Also

PCCreate(), PCSetType(), PCType (for list of available types), PC

### Level

beginner

### Location

src/ksp/pc/impls/tfs/tfs.c

### Implementations

PCTFS_giop in src/ksp/pc/impls/tfs/comm.c
PCTFS_grop in src/ksp/pc/impls/tfs/comm.c
Index of all PC routines
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Index of all manual pages