[petsc-users] Multigrid preconditioner parameters

[Jed Brown]

Feng Xing <snakexf at gmail.com> writes:
> It’s a variation of 3d Poisson equation ( -Delta u=f, u is unknown, f
> is a given function ). Mathematically, they have similar properties.

Variable coefficients?  Negative shift?  Geometry?  (These totally
change the behavior of the equation.)  Or really just a Laplacian in a
nice domain?

> So, I didn’t precise the details to make it look like too
> complicated. Numerically, the discretisation is by the standard finite
> element method or the finite volume method.

So this is a test problem and nobody cares about the answer?  You're
using it as a proxy for something else?

It is extremely common to reach misleading conclusions when using the
Laplacian as a test.  If you really care about solving this particular
problem efficiently, there are a myriad of techniques for improving
performance by orders of magnitude.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 818 bytes
Desc: not available
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20150529/2699cf69/attachment.pgp>