|-pc_factor_levels <k>||- number of levels of fill for ILU(k)|
|-pc_factor_in_place||- only for ILU(0) with natural ordering, reuses the space of the matrix for its factorization (overwrites original matrix)|
|-pc_factor_diagonal_fill||- fill in a zero diagonal even if levels of fill indicate it wouldn't be fill|
|-pc_factor_reuse_ordering||- reuse ordering of factorized matrix from previous factorization|
|-pc_factor_fill <nfill>||- expected amount of fill in factored matrix compared to original matrix, nfill > 1|
|-pc_factor_nonzeros_along_diagonal||- reorder the matrix before factorization to remove zeros from the diagonal, this decreases the chance of getting a zero pivot|
|-pc_factor_mat_ordering_type <natural,nd,1wd,rcm,qmd>||- set the row/column ordering of the factored matrix|
|-pc_factor_pivot_in_blocks||- for block ILU(k) factorization, i.e. with BAIJ matrices with block size larger than 1 the diagonal blocks are factored with partial pivoting (this increases the stability of the ILU factorization|
For BAIJ matrices this implements a point block ILU
The "symmetric" Section 1.5 Writing Application Codes with PETSc of this preconditioner is not actually symmetric since L is not transpose(U) even when the matrix is not symmetric since the U stores the diagonals of the factorization.
If you are using MATSEQAIJCUSPARSE matrices (or MATMPIAIJCUSPARSE matrices with block Jacobi), factorization is never done on the GPU).
|1.||- T. Dupont, R. Kendall, and H. Rachford. An approximate factorization procedure for solving self adjoint elliptic difference equations. SIAM J. Numer. Anal., 5, 1968.|
|2.||- T.A. Oliphant. An implicit numerical method for solving two dimensional timedependent diffusion problems. Quart. Appl. Math., 19, 1961.|
|3.||- TONY F. CHAN AND HENK A. VAN DER VORST, APPROXIMATE AND INCOMPLETE FACTORIZATIONS, Chapter in Parallel Numerical Algorithms, edited by D. Keyes, A. Semah, V. Venkatakrishnan, ICASE/LaRC Interdisciplinary Series in Science and Engineering, Kluwer.|