Stefan, could you have a look at the page again?
On Wed, Jun 5, 2013 at 2:25 PM, Stefan Krastanov <[email protected] > wrote: > 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 <[email protected]> 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 <[email protected]> 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 <[email protected]>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 < >>>> [email protected]> 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 < >>>>> [email protected]> 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 <[email protected]> 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 >>>>>>> <[email protected]> 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 [email protected]. >>>>>>> > To post to this group, send email to [email protected]. >>>>>>> > 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 [email protected]. >>>>>>> To post to this group, send email to [email protected]. >>>>>>> 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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