[Users] questions about working elliptic solver thorns

[Comer Duncan]

Hi Erik,

Frank suggested you might be an appropriate person to ask about elliptic
solver thorns that work in the current release of ET. I have, as you know,
built Hilbert and have built the development version.

I am wanting to write a thorn which prepares a geon, approximated by
initial data which has toroidal symmetry and is bounded. The desired
distribution would be placed on the r axis in cylindrical coordinates and
have a gaussian distribution. In the actual application, of course the
initial data would be interpolated onto a Cartesian coordinate mesh or
meshes.  I just want to solve the Hamiltonian constraint and have the
initial data be time-symmetric. This sounds like a pretty simple thing to
do. I think I could start with Brill and put q to my purposes and pretty
much get out what I want.  However, the IDBrill does not seem to work.
Also, I am wondering what kinds of elliptic solvers you know of that are
fully supported in ET?  Frank mentioned a petsc thorn. It does not get
downloaded and built by default and looking at the einsteintoolkit.th file
it is mentioned in:

# CactusElliptic thorns
!TARGET   = $ARR
!TYPE     = git
!URL      = https://bitbucket.org/cactuscode/cactuselliptic.git
!REPO_PATH= $2
!CHECKOUT = CactusElliptic/EllPETSc CactusElliptic/TATPETSc
CactusElliptic/EllBase
#DISABLED CactusElliptic/EllPETSc
CactusElliptic/EllSOR
CactusElliptic/TATelliptic
#DISABLED CactusElliptic/TATPETSc

However, what's with the DISABLED reference to EllPETSc is a bit
concerning. So before I go though the exercise to look more into the
EllPETSc, I thought  I'd ask whether the EllPETSc thorn is fully compatible
with Hilbert?

Can you thus please bring me up to the current moment on just what elliptic
solvers are in use for initial data construction in Hilbert?  I know many
people have been focussing on the multiple BH problem, so there's not much
traffic anymore about Brill.  I do want to run Brill though and also do the
"geon" problem.

Thanks for your advice and any pointers you can give.

Comer
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