[gmx-developers] Inconsistent force calculating result between generic kernel and interaction-specific kernel?

[Mark Abraham]

On Sat, Jun 8, 2013 at 12:59 PM, francesco oteri
<francesco.oteri at gmail.com>wrote:

> H Mark,
> I had a similar problem recently and, eventually, I figured out the cause
> was the compiler version.
> I was using gcc4.1 and my problem got solved using a more recent version.
> Actually, this issue
> in the website is clearly stated. So, which compiler are you using?
> Could you report an example of inconsistency?
>

That warning has been there many years, but AFAIK nobody ever identified
the real problem (if it exists). Nevertheless, there is no excuse for using
both GROMACS and such an old compiler! :-)

Mark


> Francesco
>
>
> 2013/6/8 Mark Abraham <mark.j.abraham at gmail.com>
>
>>
>>
>>
>> On Sat, Jun 8, 2013 at 1:44 AM, Mark Tianwu Zang <zangtw at gmail.com>wrote:
>>
>>> Dear all,
>>> I have inserted only a few lines after update() in md.c to monitor how
>>> forces change after every step. My codes are very simple, just like:
>>>
>>> for i=0 to md->nalloc
>>>  fprintf f[i][0], f[i][1], f[i][2]
>>>
>>
>> That seems like the hard way to do it, with nstfout available in the .mdp
>> file.
>>
>> However, I found the results of my output become quite different after
>>> exporting GMX_NB_GENERIC=1, which means the forces calculated by generic
>>> kernel and interaction-specific kernel are not the same. I am a little
>>> confused now.. It this phenomena quite normal or I ignored something
>>> important?
>>>
>>
>> AFAIK the generic kernel should serve as a reference for the
>> interaction-specific kernels. If not, there might a problem to fix. Hard to
>> say without context.
>>
>> Mark
>>
>> Thanks a lot!
>>> -Mark
>>>
>>>
>>>
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>>
>>
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>
>
>
> --
> Cordiali saluti, Dr.Oteri Francesco
>
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