Hi,
I've just tested with -ksp_type fgmres with rtol of 1.e-5 with 8 proceesors.
It 's much better, although the last value still has some difference at
.638e-2 and .635e-2. The original one was done with the default precon and
solver.
Btw, if I use hypre as the precond then the value with 1 or
Oh btw, here's the output when KSPSetTolerances = 1.0e-5.
1:
0 KSP preconditioned resid norm 5.509130713952e+01 true resid norm
3.411770553001e+01 ||Ae||/||Ax|| 1.e+00
1 KSP preconditioned resid norm 6.561453237357e+00 true resid norm
8.697577384386e+00 ||Ae||/||Ax||
I assume you are setting a relative tolerance. This is just a vector norm so
it will increase with dimension, and therefore the absolute difference will tend
to increase. You can set an absolute tolerance as well if this is what you want.
Matt
On 6/16/07, Ben Tay zonexo at gmail.com wrote:
Ben,
On Sat, 16 Jun 2007, Ben Tay wrote:
Hi,
I am trying to use PETSc to solve my poisson eqn. In the past, when I'm not
using MPI, I set KSPSetTolerances to 1.0e-5. This seems to be good enuff.
Now, I'm trying to use PETSc with MPI to solve the eqn. I am using a very
small no. of
