On Fri, Aug 4, 2017 at 6:19 PM, Francesco Bonazzi <franz.bona...@gmail.com> wrote:
> > > On Friday, 4 August 2017 17:34:25 UTC-4, Aaron Meurer wrote: >> >> You can try this, but I foresee problems reusing I=sqrt(-1) the complex >> number as i the quaternion. Mathematically they aren't the same thing, but >> even in terms of SymPy, ImaginaryUnit is burdened with things like >> assumptions, which might cause issues with quaternions. >> > > Implementing quaternions should be simple. Deciding how they interact with > the rest of SymPy may be more complicated. > If you implement them like Ondrej suggested, as a 4-tuple, they will interact badly. Even just adding a scalar to a quaternion will be difficult to make work, as the scalar x would have to be converted to (x, 0, 0, 0) first. On the other hand, if the quaternions i, j, and k are just special noncommutative expressions, then they will interact just fine, because SymPy already knows how to deal with noncommutative expressions. The only hard thing will be making things like i**2 and i*j auto-simplify (if desired). The former can be done with _eval_power, and the latter with Mul postprocessors. > >> And maybe even you could do something with the Mul processors to make >> them auto-simplify, if that's what is desired. >> > > I would suggest an immediate evaluation in this case. > > Maybe a Quaternion class is the simplest way to implement quaternions. > What do you mean by a Quaternion class? Are you thinking something more like my or Ondrej's suggestion? Aaron Meurer > -- > 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 post to this group, send email to sympy@googlegroups.com. > Visit this group at https://groups.google.com/group/sympy. > To view this discussion on the web visit https://groups.google.com/d/ > msgid/sympy/803df12b-57f4-4f3c-a82e-f7cdbf95d9d9%40googlegroups.com > <https://groups.google.com/d/msgid/sympy/803df12b-57f4-4f3c-a82e-f7cdbf95d9d9%40googlegroups.com?utm_medium=email&utm_source=footer> > . > > For more options, visit https://groups.google.com/d/optout. > -- 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 post to this group, send email to sympy@googlegroups.com. Visit this group at https://groups.google.com/group/sympy. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/CAKgW%3D6L2ZxAb1tu%3D7Uto4Y%3D-uLu0huy6Yg27D82%3D1VAXNckkWg%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
