[petsc-users] How to use

[Sharp Stone]

Hi all,

In the ex19, specifically from Lines 581-587, about the "invert the system"
part,

581:             /* invert the system:582:              [ dfu / du
0        0        0    ][yu] = [fu]583:              [     0    dfv /
dv     0        0    ][yv]   [fv]584:              [ dfo / du dfo / dv
dfo / do     0    ][yo]   [fo]585:              [ dft / du dft / dv
 0    dft / dt ][yt]   [ft]586:              by simple
back-substitution587:            */

 I realized u and v are independent variables, but even so, the first two
rows should be both containing dfu/dv and dfv/du terms just like the 3rd
and 4th rows, do I miss some points?

Thank you in advance!

On Thu, Oct 2, 2014 at 3:02 PM, Jed Brown <jed at jedbrown.org> wrote:

> Sharp Stone <thronesf at gmail.com> writes:
>
> > Hi all,
> >
> > I'm sorry I'm still confusing that if I have calculated the Jacobian
> > elements, how can I go ahead to solve the linear system with dof>1 at
> each
> > node? The example code ex19 solves the linear system with Guass-Seidel
> > method,
>
> As we just said, the same code (ex19.c) can use many different methods.
> The default method is Newton-Krylov with block Jacobi preconditioning.
> Run with -snes_view to see details.
>



-- 
Best regards,

Feng
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