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 -- 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/CABKqA0bsy8Ux5p8j6s%2BS-THmwgaKrtXSjM4GjaOTt9Mh2h%2BZRQ%40mail.gmail.com.
