# [mesa-users] A control like delta_lgTeff_limit for seismic values

Robert Farmer rjfarmer at asu.edu
Wed Oct 5 13:59:03 EDT 2016

Hi
There doesn't appear to be any so you'll need to make one yourself in
run_star_extras. Here is a copy of something i sent previously to the list
for constraining the timestep based on radius changes:

(Untested)

In extras_startup:
!Initialize the varaible
s%xtra1=0.d0

extras_finish_step:
!Set this to the current value after a step
s%xtra1=s%log_R

extras_check_model:

!Check if the current value vs the previous value differ by some amount
if( abs( 10**s%xtra1 - 10**s%log_R) > EPS) then
extras_check_model = retry
s% dt = s%dt * SOME_SCALE_FACTOR
end if

This will save the stars radius in s%xtra1, then in the next step we can
compare the current value with the last value. Then at the end of this step
we will save the new radius in xtra1 again.

Also from pablo's suggestion, if you only want the next step to be smaller,
rather than forcing a retry, replace the if statement with this one.

if( abs( 10**s%xtra1 - 10**s%log_R) > EPS) then
s% dt_next = min(s% dt_next, s%dt * SOME_SCALE_FACTOR)
end if

Let me know if that helps

Rob

On Wed, Oct 5, 2016 at 10:17 AM, Earl Bellinger <bellinger at mps.mpg.de>
wrote:

> Hello, are there any controls like delta_lgTeff_limit to limit the
> amount by which a seismic value may change in a single time step, such
> as the large and small frequency separations, the fundamental period,
> or frequency nearest to \nu_\max?
>
> Best regards,
> Earl Bellinger
>
>
>
> ---
> www.earlbellinger.com
> Earl Bellinger, Ph.D. Candidate
> Department of Astronomy, Yale University
> Stellar Ages & Galactic Evolution Group, Max Planck Institute
>
> ------------------------------------------------------------
> ------------------
> Check out the vibrant tech community on one of the world's most
> engaging tech sites, SlashDot.org! http://sdm.link/slashdot
> _______________________________________________
> mesa-users mailing list
> mesa-users at lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/mesa-users
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.mesastar.org/pipermail/mesa-users/attachments/20161005/fcbdcf85/attachment.html>