[petsc-users] Variable ordering in PC FieldSplit

[Barry Smith]

   PCFieldsplit is officially neutral as to the arrangement. One can define IS's to select any arbitrary subset of variables for each field.

   Unofficially we generally recommend node major order, it generally is more computationally efficient and the code is a bit easier to use with this default.

    Barry

On Jul 9, 2013, at 8:41 PM, subramanya sadasiva <subramanya.g at gmail.com> wrote:

> I have a small question about the use of PC field split, does it expect variables to be arranged in a particular fashion? Should it be variable major (all degrees of freedom corresponding to the first followed by all degrees of freedom corresponding to the next) or node major ( all degrees of freedom corresponding to each node - with a sub block structure . Is there some way of switching between the two ?
> Thanks, 
> Subramanya Sadasiva