[petsc-users] BLOCK INVERSE FOR ILU

[Frank Bramkamp]

Dear PETSc team,

I have a general question regarding the implementation of the inverse
For the ILU factorization.

I am looking e.g. on the implementation for block size 6 for the BAIJ matrix format in serial:
src/mat/impls/baij/seq/dgefa6.c

I wonder:
You are using pivoting in the inverse computation.

But if one changes the position of elements or rows, do we not have to apply an inverse permutation at the end
to get the inverse of the original matrix to some column ?!  Otherwise it is the inverse of the permutated matrix ?!

I am not quite sure if one has to do this in principle or if my understanding is not quite correct.
Maybe I miss something in your code.


Thanks, Frank