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.
