[petsc-users] help about my ts program

[Xuan YU]

On Jul 2, 2010, at 2:21 PM, Jed Brown wrote:

> On Fri, 2 Jul 2010 14:08:14 -0400, Xuan YU <xxy113 at psu.edu> wrote:
>> If I don't provide Jacobian, it will be:  type: euler
>>                   						  total number of nonlinear solver  
>> iterations=0
>> 								  total number of linear solver iterations=0
>
> The default TS is the simplest possible integrator, forward Euler.  Of
> course this doesn't do any solves (no SNES) and is not appropriate for
> stiff systems.  Run with -ts_type theta for something more likely to
> work (and which will use SNES).
>
>> [0]PETSC ERROR: Floating point exception!
>> [0]PETSC ERROR: User provided compute function generated a Not-a- 
>> Number!
>
> Euler is unstable for your problem, this should have nothing to do  
> with
> the way you specified the Jacobian.
>


I tried beuler and pseudo, and I got the errors:

>> [0]PETSC ERROR: Floating point exception!
>> [0]PETSC ERROR: User provided compute function generated a Not-a- 
>> Number!

        [0]PETSC ERROR: User provided function() line 216 in /work/ 
petsc/pihm.c(which is ierr = TSStep(ts,&its,&ftime);CHKERRQ(ierr);)



> Jed
>

Xuan YU
xxy113 at psu.edu