Jack:
I'm getting started on creating documentation right now; it should end up looking very similar to Elemental's.
The detailed instruction will be very helpful, especially
the sparse matrix data structures. Notify us when the documentation is out.
Is this a sparse Cholesky direct solver?
More or less. It currently supports LDL^T and LDL^H factorizations without pivoting, and the latter certainly works for Hermitian positive-definite matrices. The current implementation is slightly more general than Cholesky and should achieve roughly the same performance.
Currently, only mumps supports parallel sparse Cholesky direct solver.
Yours will be a good addition to the petsc external solvers.
Thanks! I'll do my best to help with the integration when the time comes.
Please keep in mind that there is not _yet_ any support for pivoting, as I needed Clique's functionality for indefinite complex symmetric matrices which are nice enough to be factored accurately without pivoting.
Petsc users likely use it as a preconditioner.
In case of zero pivot, you may provide a routine/option for adding a small
shift?
Yes, that is what I was thinking. For instance, for Helmholtz equations, one can get away with very small positive imaginary shifts (the physically corresponds to slightly damping waves).
Clique's nested dissection is built on top of a nodal graph bisection routine which uses a custom interface to parmetis; I suspect that the graph partitioning is currently the least scalable part of the black-box interface due to KLFM refinement being so hard to parallelize.
Xuan has almost finished the petsc-elemental interface
(see petsc-dev/src/mat/impls/elemental/).
We would appreciate if you can take a look at it and give us
your comments/suggests.
I just took a quick look and will make time to go over it in detail later today. I'll send out patch if I have any concrete suggestions.
Jack
Xuan will take a look at this.
Hong