On 12/20/13 3:40 PM, Que Cat wrote:
Barry,
It said that "No support for this operation for this object type!
Matrix format mpiaij does not have a built-in PETSc LU!".
Try with -pc_factor_mat_solver_package mumps (superlu_dist)
If you didn't install them reconfigure with:
--download-scalapack=1
--download-mumps=1
or:
--download-superlu_dist=1
Or just run sequentially
Anton
I run it with option "|-snes_monitor -ksp_monitor_true_residual
-snes_converged_reason -ksp_converged_reason|." and received :
0 SNES Function norm 1.414213647226e-01
0 KSP preconditioned resid norm 8.424084241999e+08 true resid norm
1.414213647226e-01 ||r(i)||/||b|| 1.000000000000e+00
1 KSP preconditioned resid norm 1.354908290122e-02 true resid norm
1.424694873074e-01 ||r(i)||/||b|| 1.007411345428e+00
Nonlinear solve did not converge due to DIVERGED_LINE_SEARCH iterations 0
It looks like that the preconditioned residual converges, but the true
residual does not.
On Fri, Dec 20, 2013 at 8:30 AM, Barry Smith <[email protected]
<mailto:[email protected]>> wrote:
Run with
-snes_mf_operator -pc_type lu
I’m sorry I sent the wrong instructions before.
Barry
On Dec 20, 2013, at 7:54 AM, Que Cat <[email protected]
<mailto:[email protected]>> wrote:
> Hi Barry,
>
> Thanks for your exlanation. I used -snes_mf -pc_type lu and now
it failed with reason -3 (/* the linear solve failed */). So,
something is wrong with the function.
>
>
> On Thu, Dec 19, 2013 at 5:01 PM, Barry Smith <[email protected]
<mailto:[email protected]>> wrote:
>
> ratio is || A - Afd || /||A|| where |||| is the frobenus norm
and difference is || A - Afd ||.
>
> Try using -snes_mf -pc_type lu
>
> This can often converge even if the A you provide is wrong,
so if this convergence sine then likely the Jacobian is wrong.
>
> It is also possible that the function evaluation has a bug.
>
> http://www.mcs.anl.gov/petsc/documentation/faq.html#newton
>
>
> Barry
>
>
>
> On Dec 19, 2013, at 4:26 PM, Que Cat <[email protected]
<mailto:[email protected]>> wrote:
>
> > Hello,
> >
> > I use SNES to solve the non linear coupled equations. I have
checked the hand-coded jacobian with -snes_type test and received
the result:
> > Norm of matrix ratio 1.39606e-23 difference 1.53372e-14
(user-defined state)
> > Norm of matrix ratio 3.03157e-10 difference 0.33305 (constant
state -1.0)
> > Norm of matrix ratio 3.03157e-10 difference 0.33305 (constant
state 1.0)
> > It said that " if the ratio is O(1.e-8), the hand-coded
Jacobian is probably correct." What is the second paramenter
"difference 1.53372e-14 ...."? Does it play any role in checking
the accuracy of hand-coded jacobian?
> >
> > The SNES solver for failed with the reason -6 "the line search
failed". I tried with all other line search method stated in the
PETSC manual, but they all failed.
> >
> > I tried to figure out what is wrong with my code? Could you
please give me any recommendation to direct me how to check my
code? I appreciate your help.
> >
> > QUe
> >
>
>
