[mesa-users] variability in runs

[andres suarez]

Hello all,

I noticed that running the same model in mesa more than once doesn't always
give the same evolution.
I am using the exact same inlist and inlist_project for the different runs
and running in the same machine, but I get different results in the star
properties and in the number of output files. The different runs sometimes
give the exact same results, more often will give something similar, but
sometimes the evolution will be quite distinct.
As an example, I attach a simple inlist file used for three 73 solar mass
runs (same in three runs) and a plot of the number of zones in each run (as
an illustration of the variability found).

I am running mesa version 3851 on a linux platform on an x86_64
multi-processor computer, using ifort.
Does anyone know if there's a known reason for this? I don't know if mesa
has any non-deterministic part in it... or if rounding errors could lead to
such varying evolution.

Regards,

a.



&star_job

      mesa_data_dir = '/home/andres/Arbeit/mesa/data'

      create_pre_main_sequence_model = .false.

      change_net = .true. ! switch nuclear reaction network
      new_net_name = 'o18_and_ne22.net'

/ !end of star_job

&controls
     ! starting specifications
         initial_mass = 73 ! in Msun units
         initial_Z = 0.02
         initial_Y = -1

     ! mass gain or loss
         RGB_wind_scheme = 'Reimers'
         Reimers_wind_eta = 0.4

     ! when to stop
         xa_central_lower_limit_species(1) = 'h1'
         xa_central_lower_limit(1) = 1d-10
            ! stop when the center abundance by mass of h1 drops below this
limit.

/
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.mesastar.org/pipermail/mesa-users/attachments/20120423/24d73d06/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: compara.ps
Type: application/postscript
Size: 23195 bytes
Desc: not available
URL: <https://lists.mesastar.org/pipermail/mesa-users/attachments/20120423/24d73d06/attachment.ps>