Jed, We replaced old numerical factorization and MatSolve with faster data structure, then cleaned up MatPivotCheck() (still using previous algorithm). Changes, such as changeset: 15909:fbc1ba94d8d9 user: hong at hong-zhangs-macbook-air.local date: Wed May 12 22:17:30 2010 -0500 files: src/mat/impls/aij/seq/aijfact.c description: replace macros with inline function MatPivotCheck() for inplace lu (aij format)
could accelerate performance. Hong On Fri, Dec 3, 2010 at 4:55 AM, Jed Brown <jed at 59a2.org> wrote: > What exactly changed between Feb 1 and the petsc-3.1 release with respect to > shifting (including for (S)BAIJ). ?In Feb, I saw negative pivots and blamed > certain performance characteristics on it. ?Now I don't see them, despite > the fact that SBAIJ does not implement the same shifts that AIJ does. ?The > performance now (or with 3.1) is significantly better, but I would like to > be able to explain what's going on. ?Running with -pc_factor_shift_type none > is still working much better than Feb 1 -dev and I would like to know why. > Jed
