[petsc-users] The question of the output from ksp/ex2.c

[Stefano Zampini]

First, make sure you compiled with support for MPI by running make check

[szampini at localhost petsc]$ make check
Running test examples to verify correct installation
Using PETSC_DIR=/home/szampini/Devel/jointinversion/pkgs/petsc and
PETSC_ARCH=arch-joint
C/C++ example src/snes/examples/tutorials/ex19 run successfully with 1 MPI
process
C/C++ example src/snes/examples/tutorials/ex19 run successfully with 2 MPI
processes
C/C++ example src/snes/examples/tutorials/ex19 run successfully with hypre
C/C++ example src/snes/examples/tutorials/ex19 run successfully with mumps
Completed test examples

if you have the "2 MPI processes" output, then type

[szampini at localhost petsc]$ make -f gmakefile print VAR=MPIEXEC
mpiexec

For me, mpiexec is system-wide.

Il giorno mer 26 feb 2020 alle ore 11:38 Tsung-Hsing Chen <
barrydog505 at gmail.com> ha scritto:

> So, What should I do to use the correct mpiexec?
> Am I configure petsc with the wrong way or something should be done?
>
> Stefano Zampini <stefano.zampini at gmail.com> 於 2020年2月26日 週三 下午4:26寫道：
>
>> This is what I get
>>
>> [szampini at localhost tutorials]$ mpiexec -n 2 ./ex2 -ksp_monitor_short -m
>> 5 -n 5 -ksp_gmres_cgs_refinement_type refine_always
>>   0 KSP Residual norm 2.73499
>>   1 KSP Residual norm 0.795482
>>   2 KSP Residual norm 0.261984
>>   3 KSP Residual norm 0.0752998
>>   4 KSP Residual norm 0.0230031
>>   5 KSP Residual norm 0.00521255
>>   6 KSP Residual norm 0.00145783
>>   7 KSP Residual norm 0.000277319
>> Norm of error 0.000292349 iterations 7
>>
>> When I sequentially, I get (same output as yours)
>>
>> [szampini at localhost tutorials]$ mpiexec -n 1 ./ex2 -ksp_monitor_short -m
>> 5 -n 5 -ksp_gmres_cgs_refinement_type refine_always
>>   0 KSP Residual norm 3.21109
>>   1 KSP Residual norm 0.93268
>>   2 KSP Residual norm 0.103515
>>   3 KSP Residual norm 0.00787798
>>   4 KSP Residual norm 0.000387275
>> Norm of error 0.000392701 iterations 4
>>
>> This means you are using the wrong mpiexec
>>
>> Il giorno mer 26 feb 2020 alle ore 11:17 Tsung-Hsing Chen <
>> barrydog505 at gmail.com> ha scritto:
>>
>>> Hi,
>>>
>>> I tried to run the example in ksp/examples/tutorials/ex2.
>>> I run the code with : mpiexec -n 2 ./ex2 -ksp_monitor_short -m 5 -n 5
>>> -ksp_gmres_cgs_refinement_type refine_always
>>>
>>> the output is :
>>>   0 KSP Residual norm 3.21109
>>>   1 KSP Residual norm 0.93268
>>>   2 KSP Residual norm 0.103515
>>>   3 KSP Residual norm 0.00787798
>>>   4 KSP Residual norm 0.000387275
>>> Norm of error 0.000392701 iterations 4
>>>   0 KSP Residual norm 3.21109
>>>   1 KSP Residual norm 0.93268
>>>   2 KSP Residual norm 0.103515
>>>   3 KSP Residual norm 0.00787798
>>>   4 KSP Residual norm 0.000387275
>>> Norm of error 0.000392701 iterations 4
>>>
>>> My output(above) is twice as the ksp/examples/tutorials/output/ex2_4.out.
>>> Is this the right answer that should come out?
>>>
>>> Thanks in advance,
>>>
>>> Tsung-Hsing Chen
>>>
>>
>>
>> --
>> Stefano
>>
>

-- 
Stefano
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