Could you try the following? null = PETSc.Mat() nest_list = [[null,null],[null,null]] Anyway, I like Lawrence's patch. I'll push a fix to maint On 18 February 2016 at 21:27, Chris Eldred <[email protected]> wrote:

Hey Lawrence,

I will give that a try, thanks!

-Chris

On Wed, Feb 17, 2016 at 3:53 PM, Lawrence Mitchell <[email protected]> wrote:

...

On 17/02/16 14:47, Chris Eldred wrote:

...

Hey All,

I was wondering if anyone had used MatNest with petsc4py. I am having issues trying to create a MatNest where some of the submatrices are empty. In PETSc, I can just pass NULL in the array that I give to MatCreateNest and it works fine. However, the following code

We use it, but haven't used it with empty slots.

...

nest_list = [[None,None],[None,None]] nest_list[0][0] = some matrix nest_list[0][1] = some matrix nest_list[1][0] = some matrix A = PETSc.Mat().createNest(nest_list,comm=PETSc.COMM_WORLD)

fails with: File "Mat.pyx", line 445, in petsc4py.PETSc.Mat.createNest (src/petsc4py.PETSc.c:103202) TypeError: Cannot convert NoneType to petsc4py.PETSc.Mat

Is there an equivalent to NULL in petsc4py (there doesn't appear to be one)?

If all of the entries in nest_list are filled, everything works fine.

Any help would be appreciated!

Maybe a patch like this to petsc4py?

diff --git a/src/PETSc/Mat.pyx b/src/PETSc/Mat.pyx index f281ba0..490c58e 100644 --- a/src/PETSc/Mat.pyx +++ b/src/PETSc/Mat.pyx @@ -460,7 +460,10 @@ cdef class Mat(Object): tmp1 = oarray_p(empty_p(nr*nc), NULL, <void**>&cmats) for i from 0 <= i < mr: for j from 0 <= j < mc: - cmats[i*mc+j] = (<Mat?>mats[i][j]).mat + if mats[i][j] is None: + cmats[i*mc+j] = NULL + else: + cmats[i*mc+j] = (<Mat?>mats[i][j]).mat if isrows is not None: tmp2 = oarray_p(empty_p(nr), NULL, <void**>&cisrows) for i from 0 <= i < mr: cisrows[i] = (<IS?>isrows[i]).iset

Untested.

If you want to pass null isrows and iscols as well you'll need to do a similar thing there.

Cheers,

Lawrence

-- Chris Eldred Postdoctoral Fellow, LAGA, University of Paris 13 PhD, Atmospheric Science, Colorado State University, 2015 DOE Computational Science Graduate Fellow (Alumni) B.S. Applied Computational Physics, Carnegie Mellon University, 2009 [email protected]

-- Lisandro Dalcin ============ Research Scientist Computer, Electrical and Mathematical Sciences & Engineering (CEMSE) Extreme Computing Research Center (ECRC) King Abdullah University of Science and Technology (KAUST) http://ecrc.kaust.edu.sa/ 4700 King Abdullah University of Science and Technology al-Khawarizmi Bldg (Bldg 1), Office # 4332 Thuwal 23955-6900, Kingdom of Saudi Arabia http://www.kaust.edu.sa Office Phone: +966 12 808-0459