[petsc-dev] Need a new name for DMDAGetOwnershipRanges

[Barry Smith]

On Nov 29, 2010, at 4:09 PM, Jed Brown wrote:

> On Mon, Nov 29, 2010 at 23:04, Barry Smith <bsmith at mcs.anl.gov> wrote:
> Changing the name means introducing a new concept that doesn't exist elsewhere and boy do I hate having tons of concepts in PETSc.
> 
> Agree. 
> 
>    Plus few sane people would use this routine so changing its meaning won't effect many end users.
> 
> Disagree.  I think it's pretty common (I know at least five people, including myself, who have done this independently) to create two or more DAs that are compatible (2D matches with 3D, or cell-centered and one node-centered) and the only robust way to do these things is to pass lx,ly,lz along to the next Create (perhaps with some modifications).

   Crap. That means that the output from this newly modifed function is not what is needed by the creation routine. In fact there exists DMDASetOwnershipRanges(). What are we going to do with that? Change the meaning of DMDASetOwnershipRanges() arguments (and hence also the meaning of the final optional arguments to the DMDACreate3d() and 2d)?  For uniformaty we  need to change those also. But the changed form is more cumbersome and less natural for users, is it not? Or is it ok to change all of them? We don't have a concept of setting global ownership values for Vec and Mat (cause the meaning is a little different). Maybe a name change is in order? 

   Barry

> 
> Jed