Hi,
I used 2 packages to solve my poisson eqn, which is part of my NS
unsteady solver. One is the NSPCG solver package which uses the
compressed row format to store the A matrix. The other is PETSc. I found
that using both solvers gave me similar answers for a number of time
step. However,
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Ok, thanks to you both. It looks like I will have to rethink this one :-/
Regards,
Graham
On Fri, 27 Jul 2007, Barry Smith wrote:
Graham,
It seems unlike the matrix was preallocated; this will
definitely slow things down a great deal. Pluse
I am guessing that you are using MATAIJ format in PETSc,
so both matrices are in the same format. How about
using MatView()? Or reading in the NSPCG matrix and
subtracting as you indicate?
Matt
On 8/2/07, Ben Tay zonexo at gmail.com wrote:
Hi,
I used 2 packages to solve my poisson eqn,
You can use MatCreateSeqAIJWithArrays() to convert the NSPCG matrix into
PETSc format and then MatAXPY() to difference them and then MatNorm() to
see how large the result is.
Make sure the PETSc or hypre solver is always converging. Run with
-ksp_converged_reason and or -ksp_monitor. My
Unless the matrix values are huge then this is a big difference.
All you can do is print the difference matrix with ASCII MatView and
look for large entries. This will tell you the locations of the
trouble entries.
Barry
On Sat, 4 Aug 2007, Ben Tay wrote:
Hi,
I realised that the
