[petsc-dev] Runge-Kutta example in TS

[Gautam Bisht]

Thanks guys for your pointers.

I was wondering if for explicit scheme, TS can increase/decrease 'dt' and point out if stability condition is violated or not.

Thanks,
-Gautam.

On Jan 16, 2013, at 11:06 AM, Sean Farley wrote:

> On Wed, Jan 16, 2013 at 12:04 PM, Gautam Bisht <gbisht at lbl.gov> wrote:
>> Hi Jed,
>> 
>> Is there an example of RK in petsc-dev? I found no result by running the following command from petsc-dev/src/ts/examples/
>> 
>> grep -Ri 'TSRK' ./
> 
> This won't work because the solver types are dynamically loaded
> (nothing fancy, it's just that the code doesn't set TSRK, etc.). To
> see which time-steppers you can try, run your favorite example (mine
> is ex6.c),
> 
> $ ./ex6 -h | grep ts_
>  -ts_type <euler>: TS method (one of) euler beuler cn pseudo gl ssp theta alpha
>  -ts_max_steps <100>: Maximum number of time steps (TSSetDuration)
>  -ts_final_time <100>: Time to run to (TSSetDuration)
>  -ts_init_time <0>: Initial time (TSSetTime)
>  -ts_dt <0.000143637>: Initial time step (TSSetTimeStep)
> 
> … and many more options. But, as Matt points out, RK methods are now
> under SSP (Jed, why aren't the ARKIMEX methods shown in help?), so,
> run it again but this time pass -ts_type ssp
> 
> $ ./ex6 -ts_type ssp -h | grep _ssp
>  -ts_ssp_type <rks2>: Type of SSP method (one of) rks2 rks3 rk104
> (TSSSPSetType)
>  -ts_ssp_nstages <5>: Number of stages (TSSSPSetNumStages)