Updated with a todo list: https://github.com/sympy/sympy/wiki/Vectors-EM-framework
Try to make the wikipage easy to read. Think of this as if it was documentation for the module. @Prasoon, if what Sachin has written is incompatible with what you have in mind, just start a section below what he has written. On 5 June 2013 10:43, Stefan Krastanov <krastanov.ste...@gmail.com> wrote: > @Sachin, it would be best to finish what we have here before we starting > discussion of motion. > > I will add a TODO to the wiki page with the issues that I see (in about an > hour). > > > On 5 June 2013 10:31, Sachin Joglekar <srjoglekar...@gmail.com> wrote: > >> @Gilbert, we could also let a CoordSystem have a motion, with something >> like >> system_a.set_vel(translational = ..., angular = ....) <- this would be >> with respect to some system defined in that frame only. >> Then coordinates of this system, when expressed in some other system, >> would be functions of coordinate variables AND the 'time' variable of the >> global reference frame. >> >> >> On Wed, Jun 5, 2013 at 1:57 PM, Gilbert Gede <gilbertg...@gmail.com>wrote: >> >>> Sachin, >>> I like where you are going with this. If I'm interpreting it correctly, >>> each CoordinateSystem has to be attached to a ReferenceFrame, and is fixed >>> (although possibly rotated and/or translated upon coordinate system >>> definition) with respect to that ReferenceFrame? Prasoon, Stefan, others - >>> what are your thoughts on this? >>> >>> I think there might be some better/easier ways to access basis vectors >>> and some other issues, but that discussion can come after a consensus is >>> reached on the CoordinateSystem/ReferenceFrame distinctions. >>> >>> -Gilbert >>> >>> >>> On Wed, Jun 5, 2013 at 12:21 AM, Sachin Joglekar < >>> srjoglekar...@gmail.com> wrote: >>> >>>> @Stefan : I would recommend having a separate class for ScalarFields. >>>> Even I wasn't sure of the need for this till yesterday, when we came across >>>> the problem of how the user would define a scalar field in any coordinate >>>> system he wants(which is not the global frame). In such cases, I propose >>>> something like the following- >>>> rho = ScalarField(6*x**2*y, c_rect1) >>>> rho.express(c_sph) >>>> >>>> If we find a better way to this this I am all for it, but for now the >>>> above seems elegant and convenient. >>>> >>>> In any case, I tried my hand at expressing a few of the steps put >>>> forward by Stefan in a mock SymPy session. I would request all of you to >>>> have a look at it and express your views (please elaborate on the reasons >>>> for any editing if done in the current code). It is a WIP obviously. >>>> The wiki link - >>>> https://github.com/sympy/sympy/wiki/Vectors-EM-framework >>>> >>>> >>>> >>>> >>>> On Wed, Jun 5, 2013 at 4:16 AM, Stefan Krastanov < >>>> krastanov.ste...@gmail.com> wrote: >>>> >>>>> Here is a quick summary from today: >>>>> >>>>> - probably scalar fields will be represented simply by SymPy >>>>> expressions where some of the symbols will have special meaning (the >>>>> coordinates) >>>>> - probably vectors will be represented like in mechanics (one object, >>>>> not necessarily a sympy expression) >>>>> >>>>> - using reference systems translated and rotated with respect to each >>>>> other is rather unclear at the moment: before continuing with the irc >>>>> meetings I would suggest that the students provide a _nice_ wiki >>>>> presenting >>>>> the answers to the questions in the previous thread and also the following >>>>> questions: >>>>> >>>>> Bellow is the question in "mathematical" terms. Transform it in >>>>> whatever way you find appropriate to fit your suggested APIs: >>>>> >>>>> - in 3D >>>>> - I have three points A, B and C. >>>>> - I use each of them as the zero of three different coordinate systems >>>>> - The A and B systems are both Cartesian but rotated by theta_AB >>>>> around axis_AB >>>>> - The C system is spherical (r, phi, theta). The theta=0 axis is >>>>> rotated wrt the z axis of A by the Euler angles alpha, beta, gamma >>>>> - I define a scalar field in A, another scalar field in B and a vector >>>>> field in C >>>>> - I want the sum of the scalar fields >>>>> - I want the gradient of that sum >>>>> - I want the convective derivative of the vector field from C wrt the >>>>> gradient from the question above >>>>> - I want to express the entities from the above 4 question in each of >>>>> the three coordinate systems. >>>>> - For all this please explicitly choose some fields for the examples >>>>> and calculate the expected results by hand (and add them to the example >>>>> session as mock results). >>>>> >>>>> I think that this will really stress test the suggested API. The only >>>>> thing missing is the time dependence needed in mechanics. I strongly >>>>> suggest that we first finish the considerations above before continuing. >>>>> >>>>> @Prasoon and Sachin, when will you be able to provide a detailed wiki >>>>> page with an example session for what is asked here? There is really no >>>>> need to hurry (officially GSoC has not started yet) so please take your >>>>> time (a week?). >>>>> >>>>> Stefan >>>>> >>>>> >>>>> On 4 June 2013 01:12, Aaron Meurer <asmeu...@gmail.com> wrote: >>>>> >>>>>> The discussion was at http://piratepad.net/KBviCWUlA3. >>>>>> >>>>>> I'm curious what you think of this kind of discussion, as opposed to >>>>>> IRC. Google docs is also an option (it has a chat). I think the >>>>>> downside is that unlike IRC, which is logged at >>>>>> http://colabti.org/irclogger/irclogger_logs/sympy, it's a little >>>>>> harder to search through these discussions afterwords. >>>>>> >>>>>> Aaron Meurer >>>>>> >>>>>> >>>>>> On Mon, Jun 3, 2013 at 4:16 PM, Stefan Krastanov >>>>>> <krastanov.ste...@gmail.com> wrote: >>>>>> > Today we had the first discussion with Prasoon and Sachin about >>>>>> their >>>>>> > projects. >>>>>> > >>>>>> > We did not progress much but at least we outlined the two general >>>>>> approaches >>>>>> > that we can use for these modules (specifically for creating vector >>>>>> fields). >>>>>> > I will give them somewhat arbitrary names here: >>>>>> > >>>>>> > - the `mechanics` way - having a Vector class that keeps all the >>>>>> information >>>>>> > about the field and it is not part of expression trees in the way >>>>>> Basic and >>>>>> > Expr are. For instance Vector(something along >>>>>> cartesian.x)+Vector(something >>>>>> > along spherical.r) will result in Vector(complex internal >>>>>> structure). >>>>>> > >>>>>> > - the `diffgeom` way - having base/unit vectors and building all >>>>>> the rest in >>>>>> > terms of their linear combinations (all this expressed as sympy >>>>>> > expressions). >>>>>> > >>>>>> > >>>>>> > >>>>>> > Prasoon and Sachin did not have the time to look at the example >>>>>> problem that >>>>>> > was given in the previous email yet (no harm done there, there is >>>>>> still some >>>>>> > time before the official starting date). Probably this will be the >>>>>> subject >>>>>> > of our next discussion. >>>>>> > >>>>>> > The next discussion was scheduled for tomorrow. After that I >>>>>> suggest that we >>>>>> > keep most of the discussions to the mailing list and the gihub wiki >>>>>> and meet >>>>>> > on irc / realtime wikis / google docs / etc once a week. >>>>>> > >>>>>> > Stefan >>>>>> > >>>>>> > -- >>>>>> > You received this message because you are subscribed to the Google >>>>>> Groups >>>>>> > "sympy" group. >>>>>> > To unsubscribe from this group and stop receiving emails from it, >>>>>> send an >>>>>> > email to sympy+unsubscr...@googlegroups.com. >>>>>> > To post to this group, send email to sympy@googlegroups.com. >>>>>> > Visit this group at http://groups.google.com/group/sympy?hl=en-US. >>>>>> > For more options, visit https://groups.google.com/groups/opt_out. >>>>>> > >>>>>> > >>>>>> >>>>>> -- >>>>>> You received this message because you are subscribed to the Google >>>>>> Groups "sympy" group. >>>>>> To unsubscribe from this group and stop receiving emails from it, >>>>>> send an email to sympy+unsubscr...@googlegroups.com. >>>>>> To post to this group, send email to sympy@googlegroups.com. >>>>>> Visit this group at http://groups.google.com/group/sympy?hl=en-US. >>>>>> For more options, visit https://groups.google.com/groups/opt_out. >>>>>> >>>>>> >>>>>> >>>>> >>>> >>> >> > -- You received this message because you are subscribed to the Google Groups "sympy" group. 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