On Tue, Mar 29, 2011 at 15:29, Thomas Witkowski <thomas.witkowski@tu-dresden.de> wrote:

Is there any example which makes use of it?

src/snes/examples/tutorials/ex28.c is a (contrived) multi-physics prototype that uses MatNest tranparently if you run with -pack_dm_mat_type nest (currently, you should add -pc_type fieldsplit -pc_fieldsplit_type additive because off-diagonal blocks are not automatically preallocated).

There are also two tests that use the low-level API:

$ grep -l MatNest src/**/tests/*.c

src/ksp/ksp/examples/tests/ex22.c

src/snes/examples/tests/ex17.c