[erlang-questions] Erlang meets physics
Thu Mar 15 01:30:07 CET 2012
On Mar 14, 2012, at 5:21 PM, CGS wrote:
> Firstly, I am glad to see physicists getting interest in Erlang.
> I see Erlang best usage in physics in few fields from Astrophysics/Astroparticle Physics/Elementary Particle Physics:
> 1. GRID;
> 2. integrated in the readout of an array of detectors for atmospheric showers,
Very true, these are great test cases for Erlang. EPICS is a project that accelerator folks wrote a long time ago (and still use and maintain to an extent)
that I think is a no-brainer application for Erlang: http://www.aps.anl.gov/epics/. It is written in C and forms a distributed data acquisition system.
> but there are few fields in which Erlang still cannot replace C/C++ (or Verilog in some cases):
> 1. accelerator (high and medium energy) physics (high frequency readout may not be compatible with Erlang, or vice-versa);
> 2. Monte Carlo simulations (even if it provides nice concurrency and code hot swap, it lacks some quite important characteristics).
> There may be some other fields from physics where Erlang may be suitable (except for communications for which is intended), but I am not the person to speak about. Nevertheless, it's good to know Erlang enters the above mentioned fields.
> Good luck!
> On Wed, Mar 14, 2012 at 4:33 PM, Pablo Platt <pablo.platt@REDACTED> wrote:
> >which the device module (in this case hp8340b) translates into the GPIB command "OPCW", and based on the
> >device address (which is governed by the atom in the first argument), dispatches it over a bus handle that it owns
> >in a state variable via bus:send_query/2.
> Can you explain how the device module translate to the GPIB command "OPCW"?
> Is it pure erlang?
> Maybe you can share some code?
> From: Jared Kofron <jared.nance@REDACTED>
> To: Erlang Questions <erlang-questions@REDACTED>
> Sent: Wednesday, March 14, 2012 1:43 AM
> Subject: Re: [erlang-questions] Erlang meets physics
> Hi Pablo-
> My first project was on embedded hardware, and basically consisted of NIFs and Webmachine dispatching.
> Pretty fun stuff.
> My current project is a little more involved, but is also pretty interesting:
> Right now the bus over which communication takes place is abstracted away by having hardware modules
> which translate API functions into their appropriate wire representation and then transmit those representations
> over a handle that they have to the correct bus.
> In essence what I've done is taken instruments and buses and given them something like behaviors.
> Hardware can perform read,write,or configure, for example. So if I want to read the center frequency of a sweeper,
> I might say
> which the device module (in this case hp8340b) translates into the GPIB command "OPCW", and based on the
> device address (which is governed by the atom in the first argument), dispatches it over a bus handle that it owns
> in a state variable via bus:send_query/2.
> At the moment, we only communicate with things over GPIB via ethernet using prologix devices to do the translation
> for us - basically glorified telnet - but it gets the job done. Everything is in a very alpha stage right now for this project,
> but it is working really nicely so far.
> On Mar 13, 2012, at 12:20 PM, Pablo Platt wrote:
> How do you interact with the hardware?
> >Do you use GPIB C libr and wrap it with a NIF?
> > From: Joe Armstrong <erlang@REDACTED>
> >To: Jared Kofron <jared.nance@REDACTED>
> >Cc: Erlang Questions <erlang-questions@REDACTED>
> >Sent: Tuesday, March 13, 2012 12:34 PM
> >Subject: Re: [erlang-questions] Erlang meets physics
> >Great news - spread the word !
> >Just for the record Erlang programmers numbers 1 and 2 (ie myself and
> >Robert Virding)
> >are both ex physicists.
> >When I lecture I often point out the similarity between causality and
> >message reception.
> >You don't know that something has happened until you get a message
> >telling that it has happened.
> >(In physics it's a ray of light, or a photon, or something -
> >forgetting entanglement for the moment)
> >In computing it's the reception of a message.
> >As a ex physicist I know that we can't say anything about simultaneous
> >events occurring
> >at different places in space-time - turn this into computer science
> >and the same arguments
> >apply to things like making sure replicated data is consistent on
> >remote sites - well you can't
> >- at least if you want to change it - Brewer's CAP theorem applies -
> >which for a physicist makes
> >perfect sense.
> >Also as an ex physicist
> I realize that things do actually happen in
> >parallel in the real world,
> >so modelling them in a sequential programming language (if I wanted to do that)
> >is big time crazy - just describe the parallel stuff in a concurrent
> >language and the program
> >writes itself. Wait a few years till we have million core computers
> >and the parallel problems
> >can be solved 1:1 on parallel computers - and programming simulations
> >and so on will be
> >really easy - but don't even think about doing it in a sequential language...
> >On Mon, Mar 12, 2012 at 2:34 AM, Jared Kofron <jared.nance@REDACTED> wrote:
> >> Hi All,
> >> I've been using Erlang at work for a few years now, and I thought I'd throw my experience out there, as
> >> my application is a little different than what you usually see on the list - I am a graduate
> student at the
> >> Center for Nuclear Physics and Astrophysics at the University of Washington, and use Erlang extensively
> >> in my work.
> >> In my experience, something that Erlang is really great at but doesn't receive much attention for these days
> >> is managing and interacting with hardware. In any physics experiment of even modest sizes, you wind up
> >> having to keep track of the state of various pieces of equipment, often modify that state, and constantly
> >> interrogate particular values. For example, we might want to change the current in a magnetic trap, turn
> >> that trap off altogether, or simply read back the voltage drop across our superconducting magnet.
> >> So far, I have deployed Erlang in this zone for two separate experiments (SNO+, a large particle physics
> >> experiment in Canada) and Project 8 (a small nuclear physics experiment here in Seattle). Both times
> >> been great successes, and I have found the reception of Erlang in this market to be great. In general, what
> >> I have done is wrap a hardware management layer with some kind of outside world interface. For SNO+, we
> >> used Webmachine and RESTful control, and for Project 8 we actually conduct all communication
> >> by using CouchDB as a message passing interface.
> >> Physicists are suspicious creatures, but once you demonstrate the feature set that you get for practically
> >> free with OTP, they see the advantage pretty quickly. On top of that, the development cycle for sophisticated
> >> applications can be greatly reduced - more than once it made my group float to the top in terms of meeting
> >> goals.
> >> In short, as far as I am concerned, Erlang has found a new niche in the world of Physics, and I intend to
> >> spread the word as much as I can!
> >> Jared
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