SNES Problem

Nils Erik Svangård nilserik at
Wed Mar 15 16:31:51 CST 2006

>    It doesn't like the nonlinear system. If you run on one process with
> -pc_type lu -snes_monitor what happens? Same problem or does it get
> past the first timestep? If it fails what if you use a much smaller time
> step, does it convergen then?

I'll try that when I have access to the code and compiler again,
however I use -snes_mf because I dont have any jacobian and I seem to
remember that using -pc_type lu dosent work when using -snes_mf, but I
might have understood wrong.
I have used the same timestep I use for the old 3-stage RK I can try a
really small timestep instead.
And it fails both when using TS or SNES, which probably almost the
same thing considering they both try to solve the first timestep.

> >
> > I have looked at rk.c, and I'm not sure how to use it.
> > Have I understood correctly that I should: get at copy of rk.c put it
> > in my working dir, somehow change it so it uses some global variables
> > or neigboring cellvalues to compute the timestep with the same
> > algorithm used in the old fortran code, then compile rk.c and make
> > sure the object file gets linked when compiling my fortran program
>    Yes,

OK, I will try my best, I have never tried something like that before.
 I rebuild petsc also?)


Nils-Erik Svangård
E-Mail: nilserik at
MSN: schweingaard at
Skype: schweingaard
Mobil: +46-(0)70-3612178

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