PCFactorSetFill#

Indicate the amount of fill you expect in the factored matrix, fill = number nonzeros in factor/number nonzeros in original matrix.

Synopsis#

#include "petscpc.h" 
PetscErrorCode PCFactorSetFill(PC pc, PetscReal fill)

Not Collective, each process can expect a different amount of fill

Input Parameters#

pc - the preconditioner context
fill - amount of expected fill

Options Database Key#

-pc_factor_fill - Sets fill amount

Notes#

For sparse matrix factorizations it is difficult to predict how much fill to expect. By running with the option -info PETSc will print the actual amount of fill used; allowing you to set the value accurately for future runs. Default PETSc uses a value of 5.0

This is ignored for most solver packages

This parameter has NOTHING to do with the levels-of-fill of ILU(). That is set with PCFactorSetLevels() or -pc_factor_levels.