Path: csiph.com!news.mixmin.net!eternal-september.org!reader01.eternal-september.org!.POSTED!not-for-mail From: Tim Rentsch Newsgroups: comp.programming Subject: Re: Another little puzzle Date: Tue, 10 Jan 2023 23:36:36 -0800 Organization: A noiseless patient Spider Lines: 46 Message-ID: <86fschmsjf.fsf@linuxsc.com> References: <87tu1diu2s.fsf@bsb.me.uk> <864jtdtkt5.fsf@linuxsc.com> <87o7rlhtsv.fsf@bsb.me.uk> <878rioifnh.fsf@bsb.me.uk> <868rinskhk.fsf@linuxsc.com> <868ridni7g.fsf@linuxsc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Injection-Info: reader01.eternal-september.org; posting-host="b8c93f532ca61670e6683a0c36d14e62"; logging-data="887949"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX18I2GH+nolT+gFo8BT3j4LVWVhAVOPtAeg=" User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.4 (gnu/linux) Cancel-Lock: sha1:awbKPAtaxEpaMinioTouVnq61Vo= sha1:MazwF2LmiZ5twBorZGUZfVKjOPA= Xref: csiph.com comp.programming:16288 "Dmitry A. Kazakov" writes: > On 2023-01-08 16:45, Tim Rentsch wrote: > >> "Dmitry A. Kazakov" writes: >> >>> Averaging arcs is equivalent to averaging angles. >> >> Angles are a one-dimensional measure. > > Averaging arcs is still equivalent to averaging angles, which is > trivial result of elementary trigonometry. > >> Finding an arc length >> "average" of points on a sphere needs a two-dimensional result. > > Points do not have arcs. > >>>> Now that I think about it, finding the point that minimizes the >>>> great circle distances squared would be at least computationally >>>> unpleasant. >>> >>> See above, it is just angles to average. >> >> Apparently you have not yet understood the problem. > > Again, averages of arcs and angles are equivalent up to a > multiplier. > >> Why don't >> you try writing a program that inputs a set of points normalized >> to be on the unit sphere, and then calculates the arc length >> average point (on the unit sphere) of those input points? > > Why don't you write a formula specifying your need? > > Programs are written according to the specifications. Numeric > programs require a properly stated problem, rather than a bunch > of words arbitrarily thrown in a meaningless sentence as above. After reading this response and also three other responses of yours (to Ben Bacarisse) down stream, I can't help but think you have little or no interest in understanding the problem, offering any useful comments about it, or trying to write a program to solve the problem. Apparently the only interest you do have is making captious remarks.