Hello,
Suppose I have a DA and I enforce the parallel decomposition during
creation by specifying the arrays lx[], ly[], lz[] in DACreate3d(). If I now
create a second DA using DARefine(), am I alays also able to obtain an
interpolation operator between the two DA's via DAGetInterpolation()?
, Matthew Knepley knepley at gmail.com wrote:
Since it just inserts a point on every edge and face (in 2D), I do not see
why it would fail. Does it?
Matt
On Wed, Sep 23, 2009 at 12:04 AM, Dave May dave.mayhem23 at gmail.comwrote:
Hello,
Suppose I have a DA and I enforce the parallel
, at 7:47 AM, Dave May wrote:
Hey Matt,
In one piece of code I have, yes the call to DAGetInterpolation() does
seem to cause a nasty crash.
A crash? Segmentation violation etc? Or an error message saying that the
decomposition is not supported? They are very different things: a crash
Hi,
I'm trying to use DMMG to solve linear Stokes flow discretised with finite
elements.
Does anyone know how to specify different matrices for the matrix associated
with the linear system and the matrix used to construct the preconditioner?
Ie, like choosing a different Amat and Bmat with
Your ix array looks fine.
If you are happy ordering the sub vector as you've indicated, just pass in
PETSC_NULL for iy when you define the VecScatter. This will indicate to just
insert/add the entries for the sub vector in order from lowest global index
largest global index.
Cheers,
Dave
On
No.
If you want to extract a parallel sub matrix, use MatGetSubMatrix().
http://www.mcs.anl.gov/petsc/petsc-as/snapshots/petsc-current/docs/manualpages/Mat/MatGetSubMatrix.html
Cheers,
Dave
On Tue, Dec 23, 2008 at 4:47 AM, Yujie recrusader at gmail.com wrote:
Hi, PETSc developer
Now, when
Hey Tim,
There is no parallel ILU support in petsc.
In parallel, the closest thing is block jacobi with ilu on each block.
This is the default parallel preconditioner in petsc.
If you have installed hypre, it provide a parallel ILU, via pilut.
Cheers,
Dave
On Thu, Nov 13, 2008 at 10:22 PM,
bsmith at mcs.anl.gov wrote:
On Sep 22, 2008, at 7:59 AM, Dave May wrote:
Why is the first pointer in PCSHELL operations the user context
whereas in MATSHELL the first pointer is of type Mat ?? Seems slightly
inconsistent.
Good question, these were done at different times and only later
Michel,
I noticed a few things. Not sure any would cause an error, but
1) You should hand control of destroying the user data type to the
PCSEHLL via PCShellSetDestroy().
2) I would also let the PCSHELL decide when the object should be setup
by calling PCShellSetSetUp(). I suppose you will
Hello,
Does anyone know the best way to perform semi coarsening using DA's?
I was trying to use the following grid sequence
level [2]: 20 x 20
level [1]: 11 x 11
level [0]: 6 x 6
where the numbers M x N corresponds to the number of nodes in the x and y
direction respectively.
However I
Hi Barry,
Does PCComputeExplicitOperator() really build B*A or A*B?
The above code appears to just be applying the preconditioner to the each
column of the identity matrix, with no reference to the original operator or
the preconditioner side.
I only wanted to clarify this fact as at one stage
Hi,
You can use PetscErrorCode PCComputeExplicitOperator(PC pc,Mat *mat)
See,
http://www-unix.mcs.anl.gov/petsc/petsc-as/snapshots/petsc-current/docs/manualpages/PC/PCComputeExplicitOperator.html
On Mon, Apr 28, 2008 at 8:19 AM, Yujie recrusader at gmail.com wrote:
Hi, everyone
How to
Hey,
MatMatMult() will work for MPIAIJ matrices. So will MatPtAP(). If you
are
ever in doubt, the easiest way (I find) to check whether I certain operation
is
supported is to just look at the source and see which ops. are defined.
I can usually find the answer with the online docs. In this
Hi,
Does anyone know how much faster (approximately) using MatMatSolve is
compared
to using PCComputeExplicitOperator(), when the PC in the latter function is
defined to be LU?
Cheers,
Dave.
On Feb 5, 2008 12:10 AM, Barry Smith bsmith at mcs.anl.gov wrote:
For sequential AIJ
Hey Vijay,
I can spot something wrong. VecGetSize gives you the global length of
the vector. However VecGetArray only gives you access to the LOCAL portion
of the vector data for that processor. Thus you need to use a local index if
you are going to set the values directly into the array.
In
For some finite element codes I've written in the past I have wanted to
leave the constraints in the matrix. Since the global FE stiffness is
assembled from element (local) contributions, a masking matrix used to zero
out entries can also be applied on the element level as well. I would
assemble
difficulties, please
don't hesitate to contact me.
Cheers,
Dave May.
On Jan 8, 2008 8:19 AM, Gideon Simpson grs2103 at columbia.edu wrote:
Is there a robust way to implement the following?
Suppose I have a block diagonal matrix
P = [A 0; 0 Q];
and I know the indices of A and Q
PetscErrorCode VecPointwiseMult(Vec w, Vec x,Vec y)
On Jan 7, 2008 9:21 PM, li pan li76pan at yahoo.com wrote:
Dear all,
I want to calculate component product of two vectors.
If I have two vectors u and v, I want to have result
as w(i) = u(i)*v(i). Is there a function in petsc to
finish
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