Yes, Carlos Roithmayr...though I have to admit I balked on problems related to P3.15, just too many substitutions, I'll probable go back and get it when I'm done.
I'm not sure how I feel about the text, it feels more like a cook book, and doesn't really give insights as to why he chose this method. Ginsberg is pretty good for that. All the variable changes, and call backs to prior problems are bit annoying. But luckily it provides solutions to all the problems, although he seems to make some non-intuitive choices in how the final solution is presented...I'm on problem set 12, and I'm hoping to grind through the whole text... On Monday, July 21, 2025 at 2:05:53 PM UTC-4 peter.st...@gmail.com wrote: > 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? >> >> frank....@gmail.com 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 asme...@gmail.com 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 >>>> <peter.st...@gmail.com> 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. >>>> > >>>> > asme...@gmail.com 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 <moore...@gmail.com> >>>> 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 <frank....@gmail.com> >>>> 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 sympy+un...@googlegroups.com. >>>> >> >> 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 sympy+un...@googlegroups.com. >>>> >> > 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 sympy+un...@googlegroups.com. >>>> > 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. 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