[petsc-users] Incomplete Cholesky Factorization in petsc

[Smith, Barry F.]

  I'm not sure what your goal is. In general two different IC(0) codes might produce slightly different factorizations based on implementation details even if they claim to run the same algorithm so I don't think there is a reason to try to compare the factors they produce.

  In addition PETSc, as well as most IC/ILU/LU  codes store the factored matrices in a "non-conventional" form that is optimized for performance so it is not easy to just pull out the "factors" to look at them or compare them.

    Barry


> On Dec 4, 2017, at 9:07 PM, Wenlong Gong <wenlonggong at gmail.com> wrote:
> 
> Hello, 
> 
> I'm trying to use the Incomplete Cholesky Factorization for a sparse matrix in petsc. I started with a 10*10 matrix and used ksp and pc in order to get the ICC(0) factor, with no fill-in, natural ordering. However, the returned factor matrix does not match with the answer I got from matlab ichol() function.
> 
> The code with the hard-coded data is attached here. I would appreciate if anyone could help check if I did anything wrong.Please let me know if there is easier way to get this incomplete cholesky factor. Thanks!
> 
> Best regards,
> Wendy
> 
> <repex.c>