[Mesa-users] Time step

[Bill Paxton]

note that there are both “limits” and “hard_limits” for time steps.  in particular,

         !### delta_lg_XH_cntr_limit

         ! If max delta is greater than this,
         ! reduce the next timestep by `delta_lg_XH_cntr_limit`/`max_delta`.

      delta_lg_XH_cntr_limit = 0.05d0

         !### delta_lg_XH_cntr_hard_limit

         ! If max delta is greater than `delta_lg_XH_cntr_hard_limit`,
         ! retry with smaller timestep.

      delta_lg_XH_cntr_hard_limit = -1

The limit impacts the setting for the NEXT timestep.  So it comes into effect for step 2 and beyond, not for step 1.

If you want step 1 to also satisfy the limit, you can set the “hard_limits” which will force a retry of step 1.


-bill


> On Nov 7, 2018, at 10:06 AM, Nsamba Benard via Mesa-users <mesa-users at lists.mesastar.org> wrote:
> 
> Hello,
> 
> I have been playing around with specifying timesteps based on only  variations in  central hydrogen abundance (Xc). The lines below specific this in the inlist.
> 
>     delta_lg_XH_cntr_limit = 0.005
>     delta_lg_XH_cntr_max = 0 
> 
> However looking at the Xc difference between models, I find a couple of consecutive models with a different difference in Xc to that specified in my inlists (See attached histogram).
> In my terminal during the runs, its clearly shown that "lg_XH_cntr" controls the steps as expected except for the first two models. 
> 
> Can someone help me understand why a few of my models don't conform to this specification? How can I fix this?
> 
> Thank you in advance for your help
> 
> Cheers,
> Benard
> ----------------------------------------------------------------------------------------------------------
> Benard Nsamba
> PhD student                                       Centro de Astrofisica
>                                                            Universidade do Porto
>                                                            Rua das Estrelas
> Tel: +351 920 404 108                      4150-762 Porto, Portugal
> E-mail: benard.nsamba at astro.up.pt <mailto:Benard.Nsamba at astro.up.pt> 
> Skype: benardnsamba
> website: https://nsambabenard2net.wixsite.com/mysite <https://nsambabenard2net.wixsite.com/mysite>
> <hist.png><inlist_2><inlist_cluster><inlist><s1.mod>_______________________________________________
> mesa-users at lists.mesastar.org
> https://lists.mesastar.org/mailman/listinfo/mesa-users
> 

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