Peter, Feel free to open an issue on the sympy github repository with precise instructions on reproducing this and we can look into it.
Jason moorepants.info +01 530-601-9791 On Tue, Jun 29, 2021 at 2:45 PM Peter Stahlecker <peter.stahlec...@gmail.com> wrote: > Dear Jason, > > Maybe it is not 'Body' vs. 'Axis', but my clumpsy programming! > The results look reasonable, but maybe my kinematic equatios are clumsy > or....? > > Take care! > > Peter > > On Tue 29. Jun 2021 at 15:24, Jason Moore <moorepa...@gmail.com> wrote: > >> Peter, >> >> Sounds like that could use some improvements. I'm not sure why the body >> fixed rotations are so much worse. >> >> Jason >> moorepants.info >> +01 530-601-9791 >> >> >> On Tue, Jun 29, 2021 at 1:00 PM Peter Stahlecker < >> peter.stahlec...@gmail.com> wrote: >> >>> Dear Jason, >>> >>> Thanks! >>> I tested it right away, and I counted the operations of an entry of rhs >>> = KM.rhs() >>> >>> For ‚Body‘ I got the count 245,633 >>> With the auxiliary frames the count was 13,235 >>> >>> Thanks again and stay healthy! >>> >>> I will keep on testing this. >>> >>> Peter >>> >>> >>> >>> >>> On Tue 29. Jun 2021 at 12:32 Jason Moore <moorepa...@gmail.com> wrote: >>> >>>> Peter, >>>> >>>> THey are equivalent other than one may provide a simpler set of >>>> direction cosine matrices and angular velocity definitions. The "Body" >>>> method should give simpler equations of motion in the end because we try to >>>> use pre-simplified forms of the equations. I don't know why you'd see >>>> faster with the intermediate frame method. >>>> >>>> You can use sympy's count_ops() function to see how many operations >>>> each symbolic form gives. The one with more operations should ultimately be >>>> slower when lambdified(). >>>> >>>> Jason >>>> moorepants.info >>>> +01 530-601-9791 >>>> >>>> >>>> On Tue, Jun 29, 2021 at 5:09 AM Peter Stahlecker < >>>> peter.stahlec...@gmail.com> wrote: >>>> >>>>> When I want to do this, it seems to me there are these possibilities: >>>>> >>>>> 1. >>>>> A = N.orientnew(‚A‘, ‚Body‘, [q1, q2, q3], ‚123‘) >>>>> This does it in one step >>>>> >>>>> 2. >>>>> I use two intermediate frames and use the word ‚Axis‘ instead of ‚Body‘ >>>>> >>>>> Geometrically, this should be the same, but it seems to me, that with >>>>> the intermediate frames establishing Kane‘s equations, lambdifying them >>>>> and >>>>> doing the numerical integration is MUCH faster. >>>>> >>>>> Are methods 1 and 2 not equivalent, as I assumed, or am I doing >>>>> something wrong? >>>>> >>>>> Thanks for any explanation! >>>>> >>>>> -- >>>>> 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+unsubscr...@googlegroups.com. >>>>> To view this discussion on the web visit >>>>> https://groups.google.com/d/msgid/sympy/d1597154-f8a8-42fa-b29b-6e8f57062441n%40googlegroups.com >>>>> <https://groups.google.com/d/msgid/sympy/d1597154-f8a8-42fa-b29b-6e8f57062441n%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 sympy+unsubscr...@googlegroups.com. >>>> To view this discussion on the web visit >>>> https://groups.google.com/d/msgid/sympy/CAP7f1AhvTHkfn8_Wc7L9i7em3QvDHn6MPBHoWwqvK9qOUw3QfA%40mail.gmail.com >>>> <https://groups.google.com/d/msgid/sympy/CAP7f1AhvTHkfn8_Wc7L9i7em3QvDHn6MPBHoWwqvK9qOUw3QfA%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 sympy+unsubscr...@googlegroups.com. >>> >> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/sympy/CABKqA0bdrLLiCY7w3yG_3sPTmx7O4Z00tn-mLSssj0rvT4m9QA%40mail.gmail.com >>> <https://groups.google.com/d/msgid/sympy/CABKqA0bdrLLiCY7w3yG_3sPTmx7O4Z00tn-mLSssj0rvT4m9QA%40mail.gmail.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 sympy+unsubscr...@googlegroups.com. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/sympy/CAP7f1Agxr30mQjCXBF31uH1qxr6OTJx2dL%2B6SkzNAyfNnytQEQ%40mail.gmail.com >> <https://groups.google.com/d/msgid/sympy/CAP7f1Agxr30mQjCXBF31uH1qxr6OTJx2dL%2B6SkzNAyfNnytQEQ%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 sympy+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/sympy/CABKqA0afGED8G8qNvLg-eYNC%2B1NEt%2BBqGZUob5N3Bc%3DWgonP6Q%40mail.gmail.com > <https://groups.google.com/d/msgid/sympy/CABKqA0afGED8G8qNvLg-eYNC%2B1NEt%2BBqGZUob5N3Bc%3DWgonP6Q%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "sympy" group. 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