[Mesa-users] unintended consequences of not properly neutralizing namelist commands.

[Warrick Ball]

Hi Amber,

> This is definitely a user issue and not code issue.

I'm not sure about that!  I'm surprised that your example "bad" inlist options led to unintended consequences, so I had a look at the block of code that sets the special rate factors.  This is most of the subroutine `set_rate_factors` in `star/job/run_star_support.f90`:

          s% rate_factors(:) = 1
          if (s% job% num_special_rate_factors <= 0) return

          call get_net_reaction_table_ptr(s% net_handle, net_reaction_ptr, ierr)
          if (ierr /= 0) return

          do i=1,s% job% num_special_rate_factors
             if (len_trim(s% job% reaction_for_special_factor(i)) == 0) cycle
             ir = rates_reaction_id(s% job% reaction_for_special_factor(i))
             j = 0
             if (ir > 0) j = net_reaction_ptr(ir)
             if (j <= 0) cycle
             s% rate_factors(j) = s% job% special_rate_factor(i)
             write(*,2) 'set special rate factor for ' // &
                   trim(s% job% reaction_for_special_factor(i)), &
                   j, s% job% special_rate_factor(i)
          end do

In your first "bad" example (reaction name ' '), I would expect the `len_trim` line to return zero, so the loop will cycle, hit the iterator's upper limit and exit, leaving the rate factors untouched.

In your second "bad" example (reaction name 'placeholder'), I would expect the dict lookup function `rates_reaction_id` to fail, which should return zero.  Then `ir` is zero, so `j` isn't modified and, again, the loop will exit without modifying the rate factors.

So your examples, as far as I can tell, should work.  That they don't may well indicate a bug, perhaps somewhere else in the code.

Could you send an inlist that reproduces the unintended consequences for your examples above?  I had a quick go at creating something myself but haven't got any "unintended" consequences.  Also, from the `write(*,2)` line in the snippet above (and my own brief experiments), the terminal output should have lines like

                  set special rate factor for rn14pg_aux          19    1.5000000000000000D+00
                  set special rate factor for rn14pg_aux          19    1.5000000000000000D+00

near the start.  That's the output when I ran with

     num_special_rate_factors = 1
     reaction_for_special_factor(1) = 'rn14pg_aux'
     special_rate_factor(1) = 1.5

What do you get with the "bad" examples?  So far, if I use the names ' ' or 'placeholder', I don't see those lines, presumably because the routine is exiting the way I expect it to, as described above, and therefore not modifying the rates.

Cheers,
Warrick



___________

Warrick Ball
Postdoc, School of Physics and Astronomy
University of Birmingham, Edgbaston, Birmingham B15 2TT
W.H.Ball at bham.ac.uk
+44 (0)121 414 4552

On Mon, 12 Apr 2021, mesa-users at lists.mesastar.org wrote:

> I want to report that things can go wrong if you don't properly nullify commands. Take for example a set of commands used to change reaction rates by a factor. One might use the following
> 
> >num_special_rate_factors = 1
> >reaction_for_special_factor(1)='reaction1'
> >special_rate_factor(1) = 2
> 
> The proper way to cancel these commands is to either 
> 1) comment them out with !
> 2) set num_special_rate_factors=0 (and possibly, leave reaction_name blank)
> or 3) set special_rate_factor(:)=1.
> 
> The following are not the proper ways, and will lead to unintended consequences
> 
> num_special_rate_factors = 1
> reaction_for_special_factor(1)=' '
> special_rate_factor(1) = 10
> 
> or
> 
> num_special_rate_factors = 1
> reaction_for_special_factor(1)='placeholder'
> special_rate_factor(1) = 10
> 
> Please learn from my experience and save yourself some time and confusion. This is definitely a user issue and not code issue.
> 
> =================================
> Dr. Amber Lauer-coles
> Postdoctoral Researcher
> Triangle Universities Nuclear Lab
> Duke University
> amber.lauer at tunl.duke.edu
> 
>