Dear Jason, Just read you latest addition about vectors and reference frames. Small question: In order to rotate a frame relative to another one, you use these terms *A.orient_axis(N, ..)* *A.orient_body_fixed(N, …)*
I assume, these are the new versions for A.orientnew(N, ‚Axis‘, …) A.orientnew(N, ‚Body, …) You might recall, that I ‚empirically‘ found that the *Body* version created much larger equations of motion compared to using ‚intermediate ‚ *Axis*‘ versions. Is it better to use *orient_body_fixed,* to avoid this issue of larger equations of motion? Thanks & take care! Peter On Sun 6. Feb 2022 at 08:19 Peter Stahlecker <[email protected]> wrote: > Dear Jason, > > Thanks a lot for your explanation! Clear! > I checked on metaclasses, but I must admit I mostly understood, that a > simple user like me should not mess with them! :-)) > > Peter > > On Sun 6. Feb 2022 at 07:49 Jason Moore <[email protected]> wrote: > >> Peter, >> >> All `dynamicsymbols` is, is: >> >> f = Function('f') >> t = symbols('t') >> f_of_t = f(t) >> >> The last line `f(t)` is generating a new class of type f, instead of >> using a predefined class (look up metaclasses). So the user, typically not >> aware of this element in Python, is confused about what they are working >> with in the last line. It is just the way SymPy Function works. There are >> open issues about trying to change it to something more sensible for the >> user to understand. >> >> Jason >> moorepants.info >> +01 530-601-9791 >> >> >> On Sun, Feb 6, 2022 at 7:39 AM Peter Stahlecker < >> [email protected]> wrote: >> >>> My question is more for my ‚general education‘ in sympy. >>> >>> I write this little program >>> >>> *from sympy.physics.mechanics import ** >>> *import sympy as sm* >>> *a = dynamicsymbols(‚a‘)* >>> *b = sm.symbols(‚b‘)* >>> >>> *print(‚type of a:‘, type(a))* >>> *print(‚type of b:‘, type(b))* >>> >>> I get this result: >>> >>> *type of a: a* >>> *type of b: class sympy.core.symbols.Symbols* >>> >>> Is seems that *a* does not have a type. How can that be? I thought in >>> python ‚everything‘ has a type. >>> >>> Thanks! >>> Any explanation is highly appreciated! >>> >>> >>> >>> >>> -- >>> 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 on the web visit >>> https://groups.google.com/d/msgid/sympy/5db2836e-44a8-428f-8b82-c56b2b2b5b20n%40googlegroups.com >>> <https://groups.google.com/d/msgid/sympy/5db2836e-44a8-428f-8b82-c56b2b2b5b20n%40googlegroups.com?utm_medium=email&utm_source=footer> >>> . >>> >> -- >> 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 on the web visit >> https://groups.google.com/d/msgid/sympy/CAP7f1Ajkjs%3DNhJOhrFXmEpLJ6nv0TM9FgHXg%3DS1kSCF-6Cw5zw%40mail.gmail.com >> <https://groups.google.com/d/msgid/sympy/CAP7f1Ajkjs%3DNhJOhrFXmEpLJ6nv0TM9FgHXg%3DS1kSCF-6Cw5zw%40mail.gmail.com?utm_medium=email&utm_source=footer> >> . >> > -- > Best regards, > > Peter Stahlecker > -- Best regards, Peter Stahlecker -- 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 on the web visit https://groups.google.com/d/msgid/sympy/CABKqA0Z9rU4%2BzFsfRmsYFHrxVSVkRNA2cmEiZS-RpR3yguON3A%40mail.gmail.com.
