[petsc-users] DIVERGED_DTOL

[w_ang_temp]

It is:
349 KSP preconditioned resid norm 3.697892503779e-01 true resid norm 3.963274534823e+04 ||r(i)||/||b|| 5.903069761695e-01
350 KSP preconditioned resid norm 1.104685840662e+02 true resid norm 1.183964449407e+07 ||r(i)||/||b|| 1.763447038252e+02
351 KSP preconditioned resid norm 1.199213228986e+02 true resid norm 1.285275666774e+07 ||r(i)||/||b|| 1.914344277014e+02
352 KSP preconditioned resid norm 1.183644579434e+02 true resid norm 1.268589721439e+07 ||r(i)||/||b|| 1.889491519909e+02
353 KSP preconditioned resid norm 1.234968225554e+02 true resid norm 1.323596647557e+07 ||r(i)||/||b|| 1.971421176662e+02
354 KSP preconditioned resid norm 2.882557881065e-01 true resid norm 3.089426814670e+04 ||r(i)||/||b|| 4.601523777979e-01
355 KSP preconditioned resid norm 2.170676916299e+02 true resid norm 2.326457175403e+07 ||r(i)||/||b|| 3.465124326697e+02
356 KSP preconditioned resid norm 5.764266225925e+00 true resid norm 6.177943120636e+05 ||r(i)||/||b|| 9.201691405543e+00
357 KSP preconditioned resid norm 1.701448294063e+04 true resid norm 1.823554008687e+09 ||r(i)||/||b|| 2.716078947576e+04
Linear solve did not converge due to DIVERGED_DTOL iterations 357
 
I cannot understand it. Which one means that the DIVERGED_DTOL occures:preconditioned resid norm, true resid norm or ||r(i)||/||b||?
What is the difference between preconditioned resid norm  and true resid norm?
    Thanks.                                  Jim







>At 2013-01-08 21:50:26,"Jed Brown" <jedbrown at mcs.anl.gov> wrote:

>Compare to the initial residual. It should be obvious if you run with -ksp_monitor_true_residual



>>On Tue, Jan 8, 2013 at 7:36 AM, w_ang_temp <w_ang_temp at 163.com> wrote:


>>Hello,

>>    I use the default dtol(1.0E+5), in my view, only when residual norm is greater than

>>dtol, the DIVERGED_DTOL occurs(||rk||>dtol*||b||). But in my project, it is not. The information is:

>>349 KSP Residual norm 3.697892503779e-01
>>350 KSP Residual norm 1.104685840662e+02
>>351 KSP Residual norm 1.199213228986e+02
>>352 KSP Residual norm 1.183644579434e+02
>>353 KSP Residual norm 1.234968225554e+02
>>354 KSP Residual norm 2.882557881065e-01
>>355 KSP Residual norm 2.170676916299e+02
>>356 KSP Residual norm 5.764266225925e+00
>>357 KSP Residual norm 1.701448294063e+04
>>Linear solve did not converge due to DIVERGED_DTOL iterations 357

>>    When iteration=357, the residual norm is 1.7e+4,it is less than dtol. Is it right?

>>    Thanks.
 
>>                                              Jim





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