Carlos Roithmayr Peter Stahlecker schrieb am Montag, 21. Juli 2025 um 19:15:52 UTC+2:
> I have used sympy.physics.mechanics, Kane's method, on many, surely over > 100 or 200 simulations. As you say, it is awsome! > Which book are yopu referring to, if I may ask? Calos Roithmyr's book? > > [email protected] schrieb am Montag, 21. Juli 2025 um 19:09:12 UTC+2: > >> I was hoping to be able to manipulate vector objects in lieu of arrays of >> components. When you work on a component basis, it's gets hard to recognize >> cross and dot products when there chain of dots and crosses. It seems like >> they could be another symbol class that has a slightly different set of >> rules. I wonder if sagemath has something, although using sagemath seems to >> be way more complicated... >> >> I am using the mechanics pkg (it's awesome!). I going through a text on >> Kane's method and trying to do every problem in the book with sympy. I run >> into difficulties with some of the proofs where you have to expand multiple >> dot product, cross products, and triple products. Currently I default to a >> tablet and just do it by hand. >> >> I can't imagine grinding on all the algebra by hand...you'd need to take >> my belt and shoelaces... >> >> On Monday, July 21, 2025 at 12:08:47 PM UTC-4 [email protected] wrote: >> >>> Yes, I think the stuff in mechanics is the best way to achieve what >>> you are looking for right now. It might be good to try to unify some >>> of this stuff at some point, since much of what is in mechanics isn't >>> really specific to mechanics or even physics. >>> >>> Aaron Meurer >>> >>> On Sat, Jul 19, 2025 at 10:44 AM Peter Stahlecker >>> <[email protected]> wrote: >>> > >>> > In sympy.physics.mechanics, I can create, say, three point P1, P2, P3 >>> > make >>> > u = P1.pos_from(P2) >>> > v = P2.pos_from(P3) >>> > >>> > and can get >>> > w = u.cross(v) >>> > >>> > but maybe I am missing a point. >>> > >>> > [email protected] schrieb am Samstag, 19. Juli 2025 um 18:10:36 >>> UTC+2: >>> >> >>> >> I would also suggest using matrix expressions for this. The main >>> issue >>> >> is that matrix expressions currently don't have a Cross operation. It >>> >> wouldn't be too hard to make one by subclassing MatrixExpr. I would >>> >> suggest opening an issue about this. >>> >> >>> >> The diff thing is another issue because currently there isn't a way >>> to >>> >> represent functions in the matrix expressions >>> >> https://github.com/sympy/sympy/issues/5855 >>> >> https://github.com/sympy/sympy/issues/19265 >>> >> >>> >> Aaron Meurer >>> >> >>> >> On Sat, Jul 19, 2025 at 1:24 AM Jason Moore <[email protected]> >>> wrote: >>> >> > >>> >> > I do not think there is a VectorSymbol type of object. If there was >>> you could imagine doing things like: >>> >> > >>> >> > R = VectorSymbol('R', 3) >>> >> > r = VectorSymbol('r', 3) >>> >> > R.diff(t).cross(r.diff(t)) >>> >> > >>> >> > We do have a MatrixSymbol object that may do what you desire. You >>> can create nx1 column matrices and then do such operations. >>> >> > >>> >> > Jason >>> >> > moorepants.info >>> >> > +01 530-601-9791 <(530)%20601-9791> >>> >> > >>> >> > >>> >> > On Thu, May 29, 2025 at 11:28 PM Frank Senkel <[email protected]> >>> wrote: >>> >> >> >>> >> >> Does sympy handle vector expressions vs instances of specific >>> vectors?..so AxBxC vs [a1,a2,a3] x [b1, b2, b3]...something like this. >>> >> >> >>> >> >> -- >>> >> >> 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 view this discussion visit >>> https://groups.google.com/d/msgid/sympy/b22199b5-810b-4371-8479-eabd71e30d0dn%40googlegroups.com. >>> >>> >>> >> > >>> >> > -- >>> >> > 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 view this discussion visit >>> https://groups.google.com/d/msgid/sympy/CAP7f1AiS2juGowfs0%3DYQcyR4mgaDZsHjRoZtwXAWEToi2r8nvg%40mail.gmail.com. >>> >>> >>> > >>> > -- >>> > 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 view this discussion visit >>> https://groups.google.com/d/msgid/sympy/70440eaa-7bc7-4ab8-a5d6-06bc7abf53f9n%40googlegroups.com. >>> >>> >>> >> -- 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 view this discussion visit https://groups.google.com/d/msgid/sympy/8241f8c7-c7cc-4e0f-9e85-a63958ef1b95n%40googlegroups.com.
