[petsc-users] amg from hypre

[hxie at umn.edu]

I printed the real residuals by computing ||b-Ax||_2  at the last column:

 equation  iter    gm_its    gmres
--------------------------------------------------------------------------------
Linear solve converged due to CONVERGED_RTOL iterations 223
 field      1       223   0.414E+00
Linear solve did not converge due to DIVERGED_ITS iterations 500
 field      2      500   0.116E-05
Linear solve did not converge due to DIVERGED_ITS iterations 500
 field      3       500   0.922E-08
Linear solve did not converge due to DIVERGED_ITS iterations 500
 field      4     500   0.182E-08
Linear solve did not converge due to DIVERGED_ITS iterations 500
 field      5      500   0.256E-09

Nothing wrong with the inner linear systems. I chose "gmres rtol" as 1.0d-6 
and "gmres atol" as 1.d-10 for the preconditioned system.

>This is the problem. The inner linear systems are just not really being
>solved. Have you looked at
>the convergence (-ksp_monitor)? You can get different nonlinear iteration
>counts this way.
>
>  Matt