Re: [hpx-users] GSoC2018 Newtonian Physics Sandbox

[Andreas Schäfer]

I just went over the changed parts of your proposal. LGTM. :-)

You're probably planning on doing this anyway, but I'll say it anyway:
you should go ahead and remove the sections that are stricken out and
resolve all comments that have been addressed, so that the doc looks
nicer.

Thanks!
-Andi


On 18:43 Mon 26 Mar , Evgeny wrote:
> Hey,
> 
> The last day proposal can be submitted. I have already made the
> cleaned version in PDF, if there is any more clarification, you can write.
> 
> Sincerely,
> Evgeny Dedov

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Re: [hpx-users] GSoC2018 Newtonian Physics Sandbox

[Evgeny]

Hey,

The last day proposal can be submitted. I have already made the
cleaned version in PDF, if there is any more clarification, you can write.

Sincerely,
Evgeny Dedov
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Re: [hpx-users] GSoC2018 Newtonian Physics Sandbox

[Andreas Schäfer]

Heya,

On 01:52 Sat 24 Mar , Evgeny wrote:
> I have a question about your bouncing spheres example. You said, that
> spheres don't actually see a grid, only neighboring spheres, but how
> neighborhood choses actually, I caught myself thinking, when I went deep
> enough into the source code of the library itself, but then realized that
> obviously it should be set by some api, but can't found which.

very good question. So, in the example code you've probably seen that
main() instantiates a SerialSimulator [1]. The
SerialSimulator actually operates on a 3d, regular grid. The reason
that the spheres only see neighboring spheres (and boundary elements)
is because Container provides adapters that translate the neighborhood
of grid cells into a neighborhood of particles (and boundaries).
Container inherits from BaseContainer[2]. This class is generated via
DECLARE_MULTI_CONTAINER_CELL() and does some behind the scenes magic.
Here is a quick rundown of what happens during simulation:

1. SerialSimulator will call update on all instances of Container in
   the 3D grid.

2. Container::update() is actually BaseContainer::update(), because
   inheritance. It receives a neighborhood object with can be
   addressed via relative coordinates (e.g. Coord<3>(-1, 0, 0)) to
   retrieve neighboring Container objects.

3. BaseContainer::update() now iterates over all elements in its
   members "spheres" and "boundaries" and calls Sphere::update() and
   Boundary::update() respectively. But instead of passing the
   neighborhood object it got from the SerialSimulator, it will pass
   on a new neighborhood object[3], a MultiNeighborhoodAdapter[4].
   This has two members, called "spheres" and "boundaries", which are
   generated in the expansion of the macro
   DECLARE_MULTI_CONTAINER_CELL().

4. These members are actually of type
   NeighborhoodIteratorHelpers::Adapter[5]. This object does the
   translation from the neighborhood that is defined on the regular
   grid towards iterating over spheres (or boundaries).

So yeah, definitely a lot going on under the hood. :-) Did this answer
your question? Feel free to ask more.

Cheers
-Andi

[1] 
https://github.com/STEllAR-GROUP/libgeodecomp/blob/master/src/examples/bouncingspheres/main.cpp#L384
[2] 
https://github.com/STEllAR-GROUP/libgeodecomp/blob/master/src/examples/bouncingspheres/main.cpp#L165
[3] 
https://github.com/STEllAR-GROUP/libgeodecomp/blob/master/src/libgeodecomp/storage/multicontainercell.h#L157
[4] 
https://github.com/STEllAR-GROUP/libgeodecomp/blob/master/src/libgeodecomp/storage/multicontainercell.h#L109
[5] 
https://github.com/STEllAR-GROUP/libgeodecomp/blob/master/src/libgeodecomp/storage/neighborhooditerator.h#L19


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Andreas Schäfer

HPC and Supercomputing for Computer Simulations
LibGeoDecomp project lead, http://www.libgeodecomp.org

PGP/GPG key via keyserver

I'm an SRE @ Google, this is a private account though.
All mails are my own and not Google's.
==

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Re: [hpx-users] GSoC2018 Newtonian Physics Sandbox

[Evgeny]

Hello,

I have a question about your bouncing spheres example. You said, that
spheres don't actually see a grid, only neighboring spheres, but how
neighborhood choses actually, I caught myself thinking, when I went deep
enough into the source code of the library itself, but then realized that
obviously it should be set by some api, but can't found which.

Sincerely,
Evgeny Dedov

2018-03-22 4:57 GMT+07:00 Andreas Schäfer :

> Hey,
>
> On 00:40 Thu 22 Mar , Evgeny wrote:
> > Hello! I spent time discovering examples and tests provided. All built
> and
> > runs ok.
>
> that's great!
>
> > So if you are more attainable in mail, It is ok, I will ask you
> > using email, if you offline in IRC.
>
> Yes, please send your questions via mail.
>
> Thanks
> -Andi
>
>
> --
> ==
> Andreas Schäfer
>
> HPC and Supercomputing for Computer Simulations
> LibGeoDecomp project lead, http://www.libgeodecomp.org
>
> PGP/GPG key via keyserver
>
> I'm an SRE @ Google, this is a private account though.
> All mails are my own and not Google's.
> ==
>
> (\___/)
> (+'.'+)
> (")_(")
> This is Bunny. Copy and paste Bunny into your
> signature to help him gain world domination!
>
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Re: [hpx-users] GSoC2018 Newtonian Physics Sandbox

[Andreas Schäfer]

Hey,

On 00:40 Thu 22 Mar , Evgeny wrote:
> Hello! I spent time discovering examples and tests provided. All built and
> runs ok.

that's great!

> So if you are more attainable in mail, It is ok, I will ask you
> using email, if you offline in IRC.

Yes, please send your questions via mail.

Thanks
-Andi


-- 
==
Andreas Schäfer

HPC and Supercomputing for Computer Simulations
LibGeoDecomp project lead, http://www.libgeodecomp.org

PGP/GPG key via keyserver

I'm an SRE @ Google, this is a private account though.
All mails are my own and not Google's.
==

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Re: [hpx-users] GSoC2018 Newtonian Physics Sandbox

[Evgeny]

Hello! I spent time discovering examples and tests provided. All built and
runs ok. So if you are more attainable in mail, It is ok, I will ask you
using email, if you offline in IRC.

Sincerely,
Evgeny Dedov

2018-03-22 0:33 GMT+07:00 Andreas Schäfer :

> Hey,
>
> just found your initial mail. :-)
>
> On 21:11 Mon 12 Mar , Evgeny wrote:
> > Hello,
> > I found intresting contributing in HPX in this GSoC
> > I'm well-versed in C++ and have some parallel programming expirience
> (MPI,
> > OpenMP)
> >
> > One of projects atreccted my attention most is legacy project Newtonian
> > Physics Sandbox, I'm in the second year of the IT department in
> Novosibirsk
> > State University, before that I studied at the physics and mathematics
> > school and attended a course "physical processes modelling" in C ++,
> where
> > during the training was modelling many processes, such as lissajous
> curves,
> > motion in a central force field, celestial bodies interaction, tunnel
> diode
> > etc. Not all of these related to Newtonian physics, I mentioned them for
> a
> > change.
>
> Cool, that sounds like a background that would make you a good fit for
> this project.
>
> > Also I haven't found any of beginnings of project, so as I understand, it
> > does not exist yet, am I right?
> > I gradually began to get acquainted with LibGeoDecomp tool, and think I
> got
> > the idea of it. If there are some other materials or advices for
> acquaintance,
> > I will be grateful.
>
> Correct, no such toolbox has been written. LibGeoDecomp has been used
> in similar settings, e.g. for smoothed particle hydrodynamics or for
> simulations of granular gasses, but these were always rather
> specialized codes and nothing generic or really reusable.
>
> I thing the first step, as it is so often, is actually to check out
> the trunk from https://github.com/STEllAR-GROUP/libgeodecomp and see
> if you can compile the library and run the tests.
>
> Cheers
> -Andi
>
>
> --
> ==
> Andreas Schäfer
>
> HPC and Supercomputing for Computer Simulations
> LibGeoDecomp project lead, http://www.libgeodecomp.org
>
> PGP/GPG key via keyserver
>
> I'm an SRE @ Google, this is a private account though.
> All mails are my own and not Google's.
> ==
>
> (\___/)
> (+'.'+)
> (")_(")
> This is Bunny. Copy and paste Bunny into your
> signature to help him gain world domination!
>
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Re: [hpx-users] GSoC2018 Newtonian Physics Sandbox

[Andreas Schäfer]

Hey,

just found your initial mail. :-)

On 21:11 Mon 12 Mar , Evgeny wrote:
> Hello,
> I found intresting contributing in HPX in this GSoC
> I'm well-versed in C++ and have some parallel programming expirience (MPI,
> OpenMP)
> 
> One of projects atreccted my attention most is legacy project Newtonian
> Physics Sandbox, I'm in the second year of the IT department in Novosibirsk
> State University, before that I studied at the physics and mathematics
> school and attended a course "physical processes modelling" in C ++, where
> during the training was modelling many processes, such as lissajous curves,
> motion in a central force field, celestial bodies interaction, tunnel diode
> etc. Not all of these related to Newtonian physics, I mentioned them for a
> change.

Cool, that sounds like a background that would make you a good fit for
this project.

> Also I haven't found any of beginnings of project, so as I understand, it
> does not exist yet, am I right?
> I gradually began to get acquainted with LibGeoDecomp tool, and think I got
> the idea of it. If there are some other materials or advices for acquaintance,
> I will be grateful.

Correct, no such toolbox has been written. LibGeoDecomp has been used
in similar settings, e.g. for smoothed particle hydrodynamics or for
simulations of granular gasses, but these were always rather
specialized codes and nothing generic or really reusable.

I thing the first step, as it is so often, is actually to check out
the trunk from https://github.com/STEllAR-GROUP/libgeodecomp and see
if you can compile the library and run the tests.

Cheers
-Andi


-- 
==
Andreas Schäfer

HPC and Supercomputing for Computer Simulations
LibGeoDecomp project lead, http://www.libgeodecomp.org

PGP/GPG key via keyserver

I'm an SRE @ Google, this is a private account though.
All mails are my own and not Google's.
==

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[hpx-users] GSoC2018 Newtonian Physics Sandbox

[Evgeny]

Hello,
I found intresting contributing in HPX in this GSoC
I'm well-versed in C++ and have some parallel programming expirience (MPI,
OpenMP)

One of projects atreccted my attention most is legacy project Newtonian
Physics Sandbox, I'm in the second year of the IT department in Novosibirsk
State University, before that I studied at the physics and mathematics
school and attended a course "physical processes modelling" in C ++, where
during the training was modelling many processes, such as lissajous curves,
motion in a central force field, celestial bodies interaction, tunnel diode
etc. Not all of these related to Newtonian physics, I mentioned them for a
change.

But I'm very interested exactly in Newtonian physics from school, so it'd
be very exciting for me to participate in such project.

Also I haven't found any of beginnings of project, so as I understand, it
does not exist yet, am I right?
I gradually began to get acquainted with LibGeoDecomp tool, and think I got
the idea of it. If there are some other materials or advices for acquaintance,
I will be grateful.

Sincerely,
Dedov Eugene (IRC: verganz)
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