[petsc-users] KSP has an extra iteration when use shell matrix
Yi Hu
y.hu at mpie.de
Tue Jan 30 14:19:18 CST 2024
Hello Barry,
Thanks for your reply. The monitor options are fine. I actually meant my
modification of snes tutorial ex1f.F90 does not work and has some
unexpected behavior. I basically wanted to test if I can use a shell
matrix as my jacobian (code is here
https://github.com/hyharry/small_petsc_test/blob/master/test_shell_jac/ex1f.F90).
After compile my modified version and run with these monitor options, it
gives me the following,
( in rhs )
( leave rhs )
0 SNES Function norm 6.041522986797e+00
++++++++++++ in jac shell +++++++++++
0 KSP Residual norm 6.041522986797e+00
=== start mymult ===
=== done mymult ===
1 KSP Residual norm 5.065392549852e-16
Linear solve converged due to CONVERGED_RTOL iterations 1
=== start mymult ===
=== done mymult ===
( in rhs )
( leave rhs )
1 SNES Function norm 3.512662245652e+00
++++++++++++ in jac shell +++++++++++
0 KSP Residual norm 3.512662245652e+00
=== start mymult ===
=== done mymult ===
1 KSP Residual norm 6.230314124713e-16
Linear solve converged due to CONVERGED_RTOL iterations 1
=== start mymult ===
=== done mymult ===
( in rhs )
( leave rhs )
( in rhs )
( leave rhs )
2 SNES Function norm 8.969285922373e-01
++++++++++++ in jac shell +++++++++++
0 KSP Residual norm 8.969285922373e-01
=== start mymult ===
=== done mymult ===
1 KSP Residual norm 0.000000000000e+00
Linear solve converged due to CONVERGED_ATOL iterations 1
=== start mymult ===
=== done mymult ===
( in rhs )
( leave rhs )
( in rhs )
( leave rhs )
3 SNES Function norm 4.863816734540e-01
++++++++++++ in jac shell +++++++++++
0 KSP Residual norm 4.863816734540e-01
=== start mymult ===
=== done mymult ===
1 KSP Residual norm 0.000000000000e+00
Linear solve converged due to CONVERGED_ATOL iterations 1
=== start mymult ===
=== done mymult ===
( in rhs )
( leave rhs )
( in rhs )
( leave rhs )
4 SNES Function norm 3.512070785520e-01
++++++++++++ in jac shell +++++++++++
0 KSP Residual norm 3.512070785520e-01
=== start mymult ===
=== done mymult ===
1 KSP Residual norm 0.000000000000e+00
Linear solve converged due to CONVERGED_ATOL iterations 1
=== start mymult ===
=== done mymult ===
( in rhs )
( leave rhs )
( in rhs )
( leave rhs )
5 SNES Function norm 2.769700293115e-01
++++++++++++ in jac shell +++++++++++
0 KSP Residual norm 2.769700293115e-01
=== start mymult ===
=== done mymult ===
1 KSP Residual norm 1.104778916974e-16
Linear solve converged due to CONVERGED_RTOL iterations 1
=== start mymult ===
=== done mymult ===
( in rhs )
( leave rhs )
( in rhs )
( leave rhs )
6 SNES Function norm 2.055345318150e-01
++++++++++++ in jac shell +++++++++++
0 KSP Residual norm 2.055345318150e-01
=== start mymult ===
=== done mymult ===
1 KSP Residual norm 0.000000000000e+00
Linear solve converged due to CONVERGED_ATOL iterations 1
=== start mymult ===
=== done mymult ===
( in rhs )
( leave rhs )
( in rhs )
( leave rhs )
7 SNES Function norm 1.267482220786e-01
++++++++++++ in jac shell +++++++++++
0 KSP Residual norm 1.267482220786e-01
=== start mymult ===
=== done mymult ===
1 KSP Residual norm 1.498679601680e-17
Linear solve converged due to CONVERGED_RTOL iterations 1
=== start mymult ===
=== done mymult ===
( in rhs )
( leave rhs )
( in rhs )
( leave rhs )
8 SNES Function norm 3.468150619264e-02
++++++++++++ in jac shell +++++++++++
0 KSP Residual norm 3.468150619264e-02
=== start mymult ===
=== done mymult ===
1 KSP Residual norm 5.944160522951e-18
Linear solve converged due to CONVERGED_RTOL iterations 1
=== start mymult ===
=== done mymult ===
( in rhs )
( leave rhs )
( in rhs )
( leave rhs )
( in rhs )
( leave rhs )
( in rhs )
( leave rhs )
( in rhs )
( leave rhs )
( in rhs )
( leave rhs )
( in rhs )
( leave rhs )
( in rhs )
( leave rhs )
( in rhs )
( leave rhs )
( in rhs )
( leave rhs )
( in rhs )
( leave rhs )
( in rhs )
( leave rhs )
( in rhs )
( leave rhs )
( in rhs )
( leave rhs )
=== start mymult ===
=== done mymult ===
Nonlinear solve did not converge due to DIVERGED_LINE_SEARCH iterations 8
Number of SNES iterations = 8
After each "Linear solve converged due to CONVERGED_ATOL iterations",
the code starts to do mymult again. So I thought it did an extra
(unwanted) KSP iteration. I would like to ask if this extra iteration
could be disabled, or maybe I am wrong about it.
Best regards,
Yi
On 1/30/24 18:35, Barry Smith wrote:
>
> How do I see a difference? What does "hence ruin my previous
> converged KSP result" mean? A different answer at the end of the KSP
> solve?
>
> $ ./joe > joe.basic
>
> ~/Src/petsc/src/ksp/ksp/tutorials*(barry/2023-09-15/fix-log-pcmpi=)*arch-fix-log-pcmpi
>
> $ ./joe -ksp_monitor -ksp_converged_reason -snes_monitor > joe.monitor
>
> ~/Src/petsc/src/ksp/ksp/tutorials*(barry/2023-09-15/fix-log-pcmpi=)*arch-fix-log-pcmpi
>
> $ diff joe.basic joe.monitor
>
> 0a1,36
>
> > 0 SNES Function norm 6.041522986797e+00
>
> > 0 KSP Residual norm 6.041522986797e+00
>
> > 1 KSP Residual norm 5.065392549852e-16
>
> > Linear solve converged due to CONVERGED_RTOL_NORMAL iterations 1
>
> > 1 SNES Function norm 3.512662245652e+00
>
> > 0 KSP Residual norm 3.512662245652e+00
>
> > 1 KSP Residual norm 6.230314124713e-16
>
> > Linear solve converged due to CONVERGED_RTOL_NORMAL iterations 1
>
> > 2 SNES Function norm 8.969285922373e-01
>
> > 0 KSP Residual norm 8.969285922373e-01
>
> > 1 KSP Residual norm 0.000000000000e+00
>
> > Linear solve converged due to CONVERGED_RTOL_NORMAL iterations 1
>
> > 3 SNES Function norm 4.863816734540e-01
>
> > 0 KSP Residual norm 4.863816734540e-01
>
> > 1 KSP Residual norm 0.000000000000e+00
>
> > Linear solve converged due to CONVERGED_RTOL_NORMAL iterations 1
>
> > 4 SNES Function norm 3.512070785520e-01
>
> > 0 KSP Residual norm 3.512070785520e-01
>
> > 1 KSP Residual norm 0.000000000000e+00
>
> > Linear solve converged due to CONVERGED_RTOL_NORMAL iterations 1
>
> > 5 SNES Function norm 2.769700293115e-01
>
> > 0 KSP Residual norm 2.769700293115e-01
>
> > 1 KSP Residual norm 1.104778916974e-16
>
> > Linear solve converged due to CONVERGED_RTOL_NORMAL iterations 1
>
> > 6 SNES Function norm 2.055345318150e-01
>
> > 0 KSP Residual norm 2.055345318150e-01
>
> > 1 KSP Residual norm 1.535110861002e-17
>
> > Linear solve converged due to CONVERGED_RTOL_NORMAL iterations 1
>
> > 7 SNES Function norm 1.267482220786e-01
>
> > 0 KSP Residual norm 1.267482220786e-01
>
> > 1 KSP Residual norm 1.498679601680e-17
>
> > Linear solve converged due to CONVERGED_RTOL_NORMAL iterations 1
>
> > 8 SNES Function norm 3.468150619264e-02
>
> > 0 KSP Residual norm 3.468150619264e-02
>
> > 1 KSP Residual norm 5.944160522951e-18
>
> > Linear solve converged due to CONVERGED_RTOL_NORMAL iterations 1
>
>
>
>
>> On Jan 30, 2024, at 11:19 AM, Yi Hu <y.hu at mpie.de> wrote:
>>
>> Dear PETSc team,
>> I am still trying to sort out my previous
>> threadhttps://lists.mcs.anl.gov/pipermail/petsc-users/2024-January/050079.htmlusing
>> a minimal working example. However, I encountered another problem.
>> Basically I combined the basic usage of SNES solver and shell matrix
>> and tried to make it work. The jacobian of my snes is replaced by a
>> customized MATOP_MULT. The minimal example code can be viewed
>> herehttps://github.com/hyharry/small_petsc_test/blob/master/test_shell_jac/ex1f.F90
>> When running with -ksp_monitor -ksp_converged_reason, it shows an
>> extra mymult step, and hence ruin my previous converged KSP result.
>> Implement a customized converged call-back also does not help. I am
>> wondering how to skip this extra ksp iteration. Could anyone help me
>> on this?
>> Thanks for your help.
>> Best wishes,
>> Yi
>>
>>
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Stay up to date and follow us on LinkedIn, Twitter and YouTube.
Max-Planck-Institut für Eisenforschung GmbH
Max-Planck-Straße 1
D-40237 Düsseldorf
Handelsregister B 2533
Amtsgericht Düsseldorf
Geschäftsführung
Prof. Dr. Gerhard Dehm
Prof. Dr. Jörg Neugebauer
Prof. Dr. Dierk Raabe
Dr. Kai de Weldige
Ust.-Id.-Nr.: DE 11 93 58 514
Steuernummer: 105 5891 1000
Please consider that invitations and e-mails of our institute are
only valid if they end with …@mpie.de.
If you are not sure of the validity please contact rco at mpie.de
Bitte beachten Sie, dass Einladungen zu Veranstaltungen und E-Mails
aus unserem Haus nur mit der Endung …@mpie.de gültig sind.
In Zweifelsfällen wenden Sie sich bitte an rco at mpie.de
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