[mesa-users] inconsistency

[Bill Paxton]

Hi,

Thanks for including the inlists and run_star_extras in your email.  As you know, that's crucial to understanding what's going on.

In this case, I think you might just need to wait under after things have been initialized, until after at least 1 step for example.

For example, try this and see what happens.   

    subroutine my_other_D_mix(id, ierr) 
	...
        if (s% model_number < 1) return						! skip before starting
        do k = 1, s% nz
            if (mod(k,100) ==0) print*, s% omega(k)
        end do
        stop
    end subroutine my_other_D_mix


The next question is why is your other_D_mix routine being called before omega has been set.

Probable answer: no one noticed and it hasn't caused any problems since things are okay after initialization ??

I'll look into this.

Bill





On Nov 5, 2016, at 9:07 AM, Martin C. wrote:

> Hi all
> 
> I think I've come across something in MESA that may contradict this from MESA paper 3:
> 
> From MESA paper 3
> 
> <image.png>
> <image.png>
> 
> MESA is supposed to provide bit for bit consistency across all platforms, independent of threads. (for those not able to see the inline screenshots).
> 
> I'm using other_D_mix in run_star_extras to calculate a diffusion coefficient. For that I need to access values from s% omega. 
> It seems that when I change OMP_NUM_THREADS from 3 to 2 the values in s% omega are different. I test this with this routine (also in attached run_star_extras)
> 
> <image.png>
> 
> I tested the above on ubuntu14, mesa 8118, latest sdk. 
> example: OMP_NUM_THREADS =2 
> <image.png>
> 
> OMP_NUM_THREADS = 3 produces:
> 
> <image.png>
> 
> 
> I also installed mesa 8118 on a mac pro with latest sdk (default of 16 threads). Here no matter what I change OMP_NUM_THREADS to I don't get the results that I get on ubuntu. Worse: running the exact same code multiple times yields different results for the printed s% omega values! (Often zeros, sometimes NaN, sometimes "random" values). 
> 
> 
> So am I misunderstanding something? What's causing this. How can I work around this problem (if it is one).
> 
> thanks!
> 
> Martin
> 
> 
> 
> 
> 
> 
> 
> 
> -- 
> Martin C.
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