[mesa-users] astero module: NaNs in profile, possibly uninitialized velocity variable?

Robert Farmer rjfarmer at asu.edu
Fri Feb 10 16:13:53 EST 2017


Hi
So the fix is just to add checks for the v_flag in profile_getval.f90
(which what the current development version uses)

if (s% v_flag) then
      val = s% v(k)/s% r(k)
end if

and for total_energy

if (s% v_flag) then
                  val = val - s% cgrav(k)*s% m_grav(k)/s% r(k) + &
                              0.5d0*s% v(k)*s% v(k)
end if

Rob



On Fri, Feb 10, 2017 at 10:56 AM, Robert Farmer <rjfarmer at asu.edu> wrote:

> Hi Warrick
>
> Thanks for the bug report, i've just run the current development version
> of mesa and its been fixed (v_dir_r comes out as 0 and total_energy as some
> non-zero value) between 8845 and 9549.
>
> I'll see if i can find what you need to do to get 8845 working.
>
> Rob
>
> On Fri, Feb 10, 2017 at 9:12 AM, Warrick Ball <wball at bison.ph.bham.ac.uk>
> wrote:
>
>> Hi,
>>
>> I think I've stumbled upon an innocent bug while working with the MESA
>> module.  This is quite easy to reproduce: in r8845, copy a new
>> star/astero/work folder and set
>>
>>    write_profile_for_best_model = .true. ! instead of .false.
>>    best_model_profile_filename = 'best.profile' ! or whatever
>>
>> then make and run.  When the star gets sufficiently close to the observed
>> data to start writing profiles, I get a star's worth of lines of the form
>>
>>                        total_energy           1                       NaN
>>                             v_div_r           1                       NaN
>>
>> I think I correctly traced the error message down to the function do_col
>> in star/private/profile.f90, which has a block checking for NaNs after a
>> call to some getval_for_profile in star/private/profile_getval.f90.
>> Rummaging through there, it looks like the problem is probably the
>> variable v, since total_energy and v_div_r have that in common.
>>
>> I haven't dug any further through the logic but my suspicion is that this
>> is a case of v(k) having not been set.  Since I'm not following the
>> velocity variable, it doesn't actually matter to me.  (The run is
>> otherwise behaving perfectly normally.)  But the NaNs were worrying,
>> though I'm sure they would also be suppressed by removing total_energy and
>> v_div_r from profile_columns.list.
>>
>> I'll try to dig a bit further to see if I can find where v is initialized.
>>
>> Cheers,
>> Warrick
>>
>>
>>
>> ------------
>> Warrick Ball
>> Postdoc, School of Physics and Astronomy
>> University of Birmingham, Edgbaston, Birmingham B15 2TT
>> wball at bison.ph.bham.ac.uk
>> +44 (0)121 414 4552
>>
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>
>
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