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Re: [Pharo-project] Differential and Integral calculus in Pharo?

by David Shaffer

On Aug 5, 2012, at 5:20 PM, Schwab,Wilhelm K wrote: > short of symbolic manipulation (e.g. maple), all we do is discretize and approximate, right? > > Integration (aka quadrature) is "easy" but numerical diff is very unstable. ODEs solve well w/ Runge-Kutta methods. > > Definitely, for some simple problems. Just to scratch the surface...Besset only provides two quadrature methods: Romberg and Simpson both of which are very problematic for many integrals (accumulation of underflow being one of the more common but I'm sure google can probably give you a longer list than I can). If I remember correctly neither of his algorithms employ adaptive step sizes (although I think that they respond to "data sources" with varying step sizes properly) so be ready for arbitrarily large errors with rapidly varying integrands. Most of the better libraries provide adaptive integrators and several variants of them because the world of "quadrature" is not one-size-fits all. The book "Numerical Recipes" (Press et al) touches the only the tip of this iceberg but its a start for those that want to go beyond Besset's book. As for diff-eqs: I don't think Besset includes Runge-Kutta or any other diff-eq integrators. RK or Adam's Bashforth are simple enough to implement, though, but again said implementation will likely be problematic, especially for very stiff equations but even in simpler cases for systems of equations that have singularities (despite the name, singularities in systems of equations are very common). More sophisticated solvers deal with these things well or one looks for specialized solvers for the problems at hand. None of this touches on problems that will likely arise from the types of problems the original poster is trying to solve (they only specified E & M). Maxwell's equations (time and space dependent PDE's) will require making both time and space discrete, which in multiple dimensions can be prohibitive due to both memory and time constraints. Normally one has to apply some knowledge of the physics to simplify the problem...or just start with a very simple problem ;-) I'm assuming the original poster will start with some problems with high degrees of symmetry and move forward from there. That is a great approach to learning numerical approaches to solving physics problems and simple tools will get them a long way. David

Aug. 6, 2012

Re: [Pharo-project] [Pharo-users] New feature in Nautilus

by Hernan Wilkinson

hey, that pretty cool! It would be great if you could press a button or something and have a diff between the methods :-) On Sun, Aug 5, 2012 at 8:48 PM, Benjamin < benjamin.vanryseghem.pharo(a)gmail.com> wrote: > Hello guys :) > > I just wanted to show you the new feature I just finished to implement > into Nautilus: the multi methods edition > > http://dl.dropbox.com/u/24369478/MultiMethods.mov > > The video is quite short (1min) but it will be integrated soon in the > image so ;) > > Some explanation: > - now you can "pin" a text area, it will "freeze" the context, so > you can edit it and save it without problems > - you can have a many as wanted > - the scroll pane is a bit clever to always keep the maximum size > for the current edition (but there are splitters, so you can set it as you > want) > - you can "unpin" a text area, and it closes it (to add: check if > there are pending changes) > - the glitch about the color is the video has been fixed already > (but I am too lazy to make another video ^^) > - the frozen area get a help text which tells the method the > source code comes from > - the corresponding button have the same help text > - clicking on the button jump to the method > > I hope you will enjoy it, and as usual if you have cool ideas, let me know > ;) > > Ben > -- *HernÃ¡n Wilkinson Agile Software Development, Teaching & Coaching* *Phone: +54 - 011 - 4311 - 8404** Mobile: +54 - 911 - 4470 - 7207 email: hernan.wilkinson(a)10Pines.com site: http://www.10Pines.com <http://www.10pines.com/>* Address: Paraguay 523, Floor 7 N, Buenos Aires, Argentina

Aug. 6, 2012

[Pharo-project] New feature in Nautilus

by Benjamin

Hello guys :) I just wanted to show you the new feature I just finished to implement into Nautilus: the multi methods edition http://dl.dropbox.com/u/24369478/MultiMethods.mov The video is quite short (1min) but it will be integrated soon in the image so ;) Some explanation: - now you can "pin" a text area, it will "freeze" the context, so you can edit it and save it without problems - you can have a many as wanted - the scroll pane is a bit clever to always keep the maximum size for the current edition (but there are splitters, so you can set it as you want) - you can "unpin" a text area, and it closes it (to add: check if there are pending changes) - the glitch about the color is the video has been fixed already (but I am too lazy to make another video ^^) - the frozen area get a help text which tells the method the source code comes from - the corresponding button have the same help text - clicking on the button jump to the method I hope you will enjoy it, and as usual if you have cool ideas, let me know ;) Ben

Aug. 5, 2012

[Pharo-project] OComplection

by Camillo Bruni

the more time I spend with OCompletion the more I think it's the wrong model: NECompletion provides in many cases way better / quicker results NOCompletion does tons of magic to increase the chances of a correct hit, neglecting - self sends - super sends - ClassSends which is basically the main source for getting nice input... I think NOCompletion should be removed. The only thing that might maintain is a Database which will give back a date for a given selector so we can sort them accordingly. But IMO that can be solved muuuuch easier. Things against NOCompletion: - not documentation whatsoever (no class comments no comments no categories... nada) - totally breaks type completion (self sends usw...) - duplication of NECompletion... Since I don't see anybody maintaining this dead body we should remove it from the system!

Aug. 5, 2012

Re: [Pharo-project] Playing with a declarative startup/shutdown subscription mechanism

by StÃ©phane Ducasse

On Aug 5, 2012, at 11:57 PM, Igor Stasenko wrote: > On 5 August 2012 23:37, StÃ©phane Ducasse <stephane.ducasse(a)inria.fr> wrote: >> I have the impression that you will need a finer order at least for the kernel. >> so putting >>> SomeClass>>startUp: quitting >>> <systemShutdown: #kernel priority: 1000> >>> self blahblah. >> >> looks to me the way to go and yes we should clean that part two. >> >> Now what is the gain to have pragma and not just a class side method returning a number? >> >> Stef >> > the downside of it, that you apparently more slower than explicit > subscription (you have to scan > over all methods with such pragma). yes this is why I propose sending a message but may be you have to send a message to all classes so this is bad too. > > i cannot remember what solution i proposed.. ah ok.. i recall. > i proposed to introduce a session-awareness. i.e. an object holds a > reference to a session object > and before each access to its some session-specific resource it should > check if session has changed or not. > and if session is obsolete, then you know that you must reinitialize > (meaning do a startup). > this is what i did in NB: it does not registering for startup, but > instead it initializing at first attempt to use it. So if nobody using > it, nothing happens (means no extra cycles burned at startup for > nothing). > This also solves nicely a problem with priority of service initialization: > - imagine service A requires service B to function, > but user code attempts to access a service A first. Now since service > A will try to access a service B first, > as result, a service B will be naturally (re)initialized first. > Like that, you don't even need to think (or make sure), who should be > (re)initialized first, because chain of priority automatically adjusts > itself according to program flow. Yes this is more modular. > > -- > Best regards, > Igor Stasenko. >

Aug. 5, 2012

Re: [Pharo-project] Playing with a declarative startup/shutdown subscription mechanism

by Igor Stasenko

On 5 August 2012 23:37, StÃ©phane Ducasse <stephane.ducasse(a)inria.fr> wrote: > I have the impression that you will need a finer order at least for the kernel. > so putting >> SomeClass>>startUp: quitting >> <systemShutdown: #kernel priority: 1000> >> self blahblah. > > looks to me the way to go and yes we should clean that part two. > > Now what is the gain to have pragma and not just a class side method returning a number? > > Stef > the downside of it, that you apparently more slower than explicit subscription (you have to scan over all methods with such pragma). i cannot remember what solution i proposed.. ah ok.. i recall. i proposed to introduce a session-awareness. i.e. an object holds a reference to a session object and before each access to its some session-specific resource it should check if session has changed or not. and if session is obsolete, then you know that you must reinitialize (meaning do a startup). this is what i did in NB: it does not registering for startup, but instead it initializing at first attempt to use it. So if nobody using it, nothing happens (means no extra cycles burned at startup for nothing). This also solves nicely a problem with priority of service initialization: - imagine service A requires service B to function, but user code attempts to access a service A first. Now since service A will try to access a service B first, as result, a service B will be naturally (re)initialized first. Like that, you don't even need to think (or make sure), who should be (re)initialized first, because chain of priority automatically adjusts itself according to program flow. -- Best regards, Igor Stasenko.

Aug. 5, 2012

Re: [Pharo-project] ScriptManager MNU #yellowButtonMenu

by StÃ©phane Ducasse

On Aug 5, 2012, at 8:48 PM, Torsten Bergmann wrote: > It works without a problem in Pharo 2.0. > > In Pharo 1.4. it worked a month ago - but with the new > summer release of Pharo the "ParagraphEditor" is now > thrown out and a switch to "SmalltalkEditor" is required. > I fixed it. > > So if you download a new Pharo 1.4 from the homepage > then try the "ConfigurationOfScriptManager-tbn.19" > which is available from the config browser. > > Lesson learned: when we provide a new update on > an already existing Pharo version (like the summer > update release for 1.4 then we should check for compatibility > or check all configs for this version) Yes and this should be done automatically. I hope that we will get that before crhstirmax > > Bye > T. >

Aug. 5, 2012

Re: [Pharo-project] Monticello changes not working

by StÃ©phane Ducasse

may be the case got worsen with the change from systemChangeNotifier to systemAnnoucer. Probably the changeSet does not get notified correctly. Stef On Aug 5, 2012, at 7:51 PM, Mariano Martinez Peck wrote: > In my case, I can reproduce it always. Each time I ask changes, not necessary slices. > Modify something in a package and see changes. > > On Sun, Aug 5, 2012 at 7:44 PM, Camillo Bruni <camillobruni(a)gmail.com> wrote: > I think it happens quite reproducible when asking for changes of packages with references (slices)... > > On 2012-08-05, at 16:20, "Sean P. DeNigris" <sean(a)clipperadams.com> wrote: > > EstebanLM wrote > >> > >> not all the time, but yes, some times it happens to me too > >> > > > > Anybody have a reproducible case? > > > > > > > > -- > > View this message in context: http://forum.world.st/Monticello-changes-not-working-tp4643184p4643198.html > > Sent from the Pharo Smalltalk mailing list archive at Nabble.com. > > > > > > > > -- > Mariano > http://marianopeck.wordpress.com >

Aug. 5, 2012

Re: [Pharo-project] Playing with a declarative startup/shutdown subscription mechanism

by StÃ©phane Ducasse

I have the impression that you will need a finer order at least for the kernel. so putting > SomeClass>>startUp: quitting > <systemShutdown: #kernel priority: 1000> > self blahblah. looks to me the way to go and yes we should clean that part two. Now what is the gain to have pragma and not just a class side method returning a number? Stef > Hi! > > Last days I was playing to replace the image startup/shutdown mechanism via a pragma subscription because I was pissed off with how difficult is to integrate the change of a new startup in the system. The idea is: > - reduce the mess on subscription/unsubscription, initialization, etc > - reduce dependencies of external packages in core packages. > > This way, if you want to subscribe a class side method to be executed on startup, you annotate it: > > SomeClass>>startUp: resuming > <systemStartup: #application> > self blahblah. > > SomeClass>>startUp: quitting > <systemShutdown: #kernel> > self blahblah. > > > Now, instead of an order in classes startup, I played with the idea of having run levels (which I named #kernel, #application and #user because I was not inspired :P). Then I replaced the whole system startup and It's working... > > The code is very simple, you can have a look at the category System-Tasks which can be downloaded from: > > MCGemstoneRepository > location: 'http://ss3.gemstone.com/ss/PharoTaskForces' > user: '' > password: '' > > SLICE-Issue-666-Playing-With-startup-GuillermoPolito.2 > > > Be careful, that package contains the startup code + the replacement of the old startup by the new one :). > > Now, I'd like to have some feedback, u like it? u buy it? which should be the names for the run levels? how many run levels should we have? :P > > Cheers, > Guille

Aug. 5, 2012

Re: [Pharo-project] Differential and Integral calculus in Pharo?

by Schwab,Wilhelm K

short of symbolic manipulation (e.g. maple), all we do is discretize and approximate, right? Integration (aka quadrature) is "easy" but numerical diff is very unstable. ODEs solve well w/ Runge-Kutta methods. ________________________________ From: pharo-project-bounces(a)lists.gforge.inria.fr [pharo-project-bounces(a)lists.gforge.inria.fr] on behalf of David Shaffer [cdshaffer(a)acm.org] Sent: Sunday, August 05, 2012 5:13 PM To: Pharo-project(a)lists.gforge.inria.fr Subject: Re: [Pharo-project] Differential and Integral calculus in Pharo? On Aug 1, 2012, at 6:03 PM, Clara Allende wrote: Hi guys, after having exhausting four months of Physics lessons, I decided that would be fun to write a program to deal with Electricity problems :) (Yeah, I'm not a normal person :P) So, I need to make differential and integral calculus, are there any libraries to do so? Or any place that I can take a look at? Thanks in advance! Cheers In case you haven't already come across it: http://sourceforge.net/projects/dhbnumerics/ In my personal experience the algorithms in the book are often naive and problematic compared to industrial-strength numerical algorithms but they are also quite often good enough for a first attempt at some numerical work. David

Aug. 5, 2012