gmres - restart and Gauss-Seidel

[Lukasz Kaczmarczyk]

Barry Smith wrote:
>  9 KSP Residual norm 3.942287795560e-03
> 10 KSP Residual norm 4.611215310185e+00
>                                             ^^^^^^^^^^^^^^^^^^^^^^
> 
>     This should never happen. This means there is an error
> in your preconditioner, your smoother is not a linear operator
> on its input variables. With GMRES, at restart the residual
> norm should hardly change at all. The fact that it shoots
> up means that the norm indicated in iteration 9 is totally wrong.
> 
>   If you run the gmres version with -ksp_monitor_true_residual
> you will see that the true residual is not actually decreasing
> like you think it is.
> 

Thank You for answer, result for which you asking are in my previous
email - look at end of the previous email. If You look there at true
residual, You will see that results are ok.

Regards,
Lukasz

2) -ksp_type fgmres -ksp_gmres_restart 100 -ksp_monitor_true_residual
  0 KSP preconditioned resid norm 8.770931682456e+05 true resid norm
8.770931682456e+05 ||Ae||/||Ax|| 2.025559907164e+06
  1 KSP preconditioned resid norm 1.466659768959e+00 true resid norm
1.466659768959e+00 ||Ae||/||Ax|| 3.387105649673e+00
  2 KSP preconditioned resid norm 2.135783619677e-01 true resid norm
2.135783619678e-01 ||Ae||/||Ax|| 4.932380991006e-01
  3 KSP preconditioned resid norm 1.342354228152e-01 true resid norm
1.342354228151e-01 ||Ae||/||Ax|| 3.100034299884e-01
  4 KSP preconditioned resid norm 7.872906297489e-02 true resid norm
7.872906297491e-02 ||Ae||/||Ax|| 1.818169828064e-01
  5 KSP preconditioned resid norm 3.414496482864e-02 true resid norm
3.414496482865e-02 ||Ae||/||Ax|| 7.885441854116e-02
  6 KSP preconditioned resid norm 2.025183908090e-02 true resid norm
2.025183908092e-02 ||Ae||/||Ax|| 4.676961897981e-02
  7 KSP preconditioned resid norm 1.023707179274e-02 true resid norm
1.023707179279e-02 ||Ae||/||Ax|| 2.364150462111e-02
  8 KSP preconditioned resid norm 4.938281368004e-03 true resid norm
4.938281368031e-03 ||Ae||/||Ax|| 1.140447230867e-02
  9 KSP preconditioned resid norm 2.373276511281e-03 true resid norm
2.373276511245e-03 ||Ae||/||Ax|| 5.480847330515e-03
 10 KSP preconditioned resid norm 1.180493643594e-03 true resid norm
1.180493643635e-03 ||Ae||/||Ax|| 2.726233291716e-03
 11 KSP preconditioned resid norm 7.142592937639e-04 true resid norm
7.142592936809e-04 ||Ae||/||Ax|| 1.649511181911e-03
 12 KSP preconditioned resid norm 4.226036746778e-04 true resid norm


3) -ksp_type fgmres -ksp_gmres_restart 10  -ksp_monitor_true_residual
 0 KSP preconditioned resid norm 8.770931682456e+05 true resid norm
8.770931682456e+05 ||Ae||/||Ax|| 2.025559907164e+06
 1 KSP preconditioned resid norm 1.466659768959e+00 true resid norm
1.466659768959e+00 ||Ae||/||Ax|| 3.387105649673e+00
 2 KSP preconditioned resid norm 2.135783619677e-01 true resid norm
2.135783619678e-01 ||Ae||/||Ax|| 4.932380991006e-01
 3 KSP preconditioned resid norm 1.342354228152e-01 true resid norm
1.342354228151e-01 ||Ae||/||Ax|| 3.100034299884e-01
 4 KSP preconditioned resid norm 7.872906297489e-02 true resid norm
7.872906297491e-02 ||Ae||/||Ax|| 1.818169828064e-01
 5 KSP preconditioned resid norm 3.414496482864e-02 true resid norm
3.414496482865e-02 ||Ae||/||Ax|| 7.885441854116e-02
 6 KSP preconditioned resid norm 2.025183908090e-02 true resid norm
2.025183908092e-02 ||Ae||/||Ax|| 4.676961897981e-02
 7 KSP preconditioned resid norm 1.023707179274e-02 true resid norm
1.023707179279e-02 ||Ae||/||Ax|| 2.364150462111e-02
 8 KSP preconditioned resid norm 4.938281368004e-03 true resid norm
4.938281368031e-03 ||Ae||/||Ax|| 1.140447230867e-02
 9 KSP preconditioned resid norm 2.373276511281e-03 true resid norm
2.373276511245e-03 ||Ae||/||Ax|| 5.480847330515e-03
10 KSP preconditioned resid norm 1.180493643635e-03 true resid norm
1.180493643635e-03 ||Ae||/||Ax|| 2.726233291716e-03
11 KSP preconditioned resid norm 8.973593571160e-04 true resid norm
8.973593570913e-04 ||Ae||/||Ax|| 2.072362665506e-03
12 KSP preconditioned resid norm 8.954054180580e-04 true resid norm