[petsc-dev] PDIPDM questions

[Pierre Jolivet]

Hello,
In my quest to help users migrate from Ipopt to Tao, I’ve a new question.
When looking at src/tao/constrained/tutorials/ex1.c, it seems that almost everything is centralized on rank 0 (local sizes are 0 but on rank 0).
I’d like to have my Hessian distributed more naturally, as in (almost?) all other SNES/TS examples, but still keep the Jacobian of my equality constraint, which is of dimension 1 x N (N >> 1), centralized on rank 0.
Is this possible?
If not, is it possible to supply the transpose of the Jacobian, of dimension N x 1, which could then be distributed row-wise like the Hessian?
Or maybe use some trick to distribute a MatAIJ/MatDense of dimension 1 x N column-wise? Use a MatNest with as many blocks as processes?

So, just to sum up, how can I have a distributed Hessian with a Jacobian with a single row?

Thanks in advance for your help,
Pierre