#include "petscpc.h" PetscErrorCode PCFactorSetDropTolerance(PC pc,PetscReal dt,PetscReal dtcol,PetscInt maxrowcount)Logically Collective on PC
| pc | - the preconditioner context | |
| dt | - the drop tolerance, try from 1.e-10 to .1 | |
| dtcol | - tolerance for column pivot, good values [0.1 to 0.01] | |
| maxrowcount | - the max number of nonzeros allowed in a row, best value depends on the number of nonzeros in row of original matrix |
| -pc_factor_drop_tolerance <dt,dtcol,maxrowcount> | - Sets drop tolerance |
There are NO default values for the 3 parameters, you must set them with reasonable values for your matrix. We don't know how to compute reasonable values.