SNESSetUp() and matrix-free options

Jed Brown jed at
Thu May 7 16:03:08 CDT 2009

Barry Smith wrote:
> I don't have a problem with (somehow) merging the two options, but I
> don't see it as a big improvement.
>    -snes_mf -snes_mf_type both or operator
> instead of -snes_mf or -snes_mf_operator
> I don't see this as a big improvement.

The difference is that

  -snes_mf -snes_mf_operator

is a conflict, but

  -snes_mf -snes_mf_type both -snes_mf -snes_mf_type operator1
-snes_mf_type operator2

is not a conflict because it collapses to

  -snes_mf -snes_mf_type operator2

This isn't a big deal when all the options are on the command line, but
it is definitely nicer if some options are sitting in .petscrc or being
pulled in with -options_file.


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