On Jun 26, 2016, at 8:30 PM, Adrian Croucher <[email protected]> wrote:

hi

Sorry, I realise now I was barking up the wrong tree in trying to use MatMFFDSetType().

What I'm actually looking for is just the equivalent of setting the command line option "-mat_fd_type ds" as default in my code- for an ordinary Jacobian matrix, not for a matrix-free method.

The doc page on MatFDColoringSetFromOptions():

http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/MatFD/MatFDColor...

mentions setting the fd type to 'wp' or 'ds', and links to pages about MATMFFD_WP and MATMFFD_DS, which is probably where I started going astray.

How do I do the equivalent of setting the option "-mat_fd_type ds" in my code? There is MatMFFDSetType() for MATMFFD, but doesn't seem to be anything like a plain MatFDSetType().

Yes, you are correct, there is no MatFDSetType() and in the SetFromOptions we totally cheat http://www.mcs.anl.gov/petsc/petsc-current/src/mat/matfd/fdmatrix.c.html#Mat... and just stick the value directly into the data structure. For now you can call PetscOptionsSetValue(NULL,"-mat_fd_type","ds") in your code (before you start using the MatFD stuff) and we'll add the routine to the master branch. Barry I didn't think anyone would care about the difference between ds and wp with MatFD.

- Adrian -- Dr Adrian Croucher Senior Research Fellow Department of Engineering Science University of Auckland, New Zealand email: [email protected]

tel: +64 (0)9 923 84611