Jason, I see now. You want to keep it open for people who know how to define vectors in multiple coordinate systems. I do feel that it should be expressed in the documentation (might already be, not at comp).
Justin Sent from my iPhone > On Oct 24, 2015, at 12:42 AM, Jason Moore <[email protected]> wrote: > > I'm not trying to quell debate and discussion. I just wanted to bring up the > reason we created the package in the first place and encourage its > consideration in future design decisions. > > > Jason > moorepants.info > +01 530-601-9791 > >> On Fri, Oct 23, 2015 at 4:47 PM, Justin <[email protected]> wrote: >> >> >>> On Friday, October 23, 2015 at 7:27:45 PM UTC-4, Nathan Goldbaum wrote: >>> >>> >>>> On Fri, Oct 23, 2015 at 6:25 PM, Justin <[email protected]> wrote: >>>> I have a terrible way of wording things.. more of a discussion between >>>> myself and the author where he mentioned that I should ask the community >>>> what they think. >>>> >>>>> On Friday, October 23, 2015 at 6:43:51 PM UTC-4, Jason Moore wrote: >>>>> Justin, >>>>> >>>>> I don't think there is a debate. We have a very nice vector >>>>> representation in the physics package, but it is based on mutable types >>>>> and isn't very general. We created the sympy.vector package to make a >>>>> more general vector object that was based on immutable types with the >>>>> idea that the physics vector could eventually be deprecated. Our new >>>>> implementation may not be general enough for the mathematicians' taste >>>>> and we are willing to improve it so that it is, but we would still want >>>>> it to eventually allow us to deprecate sympy.physics.vector. The addition >>>>> of vectors from different coordinate systems is essential to this plan. >>>>> So whatever you want to do to improve the package will have my support >>>>> but I hope that you will keep this intended use case in mind when you >>>>> think about bigger design changes. >>>> >>>> I come from a physics background and can't see when or why this would be >>>> useful so my opinion is certainly biased. As to the generality of the >>>> package there are no constrains on doing this and, bias and all, this >>>> tells me there ought to be some. I am new to contributing so I will keep >>>> my head down and add functionality as you mentioned. I am not trying to >>>> step on toes here... >>> >>> A vector (e.g. the mathematical object, not necessarily its representation) >>> should be independent of the coordinate system, no? So long as there are >>> well-defined translations between the coordinate systems, it should >>> certainly be possible to do arithmetic operations on two vectors whose >>> representations are written down in different coordinate systems. >> >> The way I see it is that well are defining two different (or the same) >> coordinate systems with different (or the same) basis and allowing >> arithmetic operations between these two different (or the same) coordinate >> system. The thing is we don't know until we make some definitions of the >> coordinate system whether the vector is well defined. For example: >> >> Say C1 is defined and the origin is set at (0,0,0). C2 is defined where >> it's y-axis aligns along C1's x-axis and origin is set at (0,0,0). Any >> scaling could be set on C2 wrt C1. Is the operation >> C1.x * C1.i + C2.y * C2.j a well-defined vector? >> >> -- >> 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. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/sympy/e1c47552-167f-4cb1-aa33-19bb896af677%40googlegroups.com. >> >> For more options, visit https://groups.google.com/d/optout. > > -- > You received this message because you are subscribed to a topic in the Google > Groups "sympy" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/sympy/63HmWN4GgCU/unsubscribe. > To unsubscribe from this group and all its topics, 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. > To view this discussion on the web visit > https://groups.google.com/d/msgid/sympy/CAP7f1AgFKCvB3BnyZejf-kCvGmoPE3%3DYqRMUF78C3mNwuMKffw%40mail.gmail.com. > For more options, visit https://groups.google.com/d/optout. -- 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. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/3610E7C5-6721-4520-90C2-17FAFD893BC2%40gmail.com. For more options, visit https://groups.google.com/d/optout.
