Path: csiph.com!feeder.erje.net!2.us.feeder.erje.net!nntp.club.cc.cmu.edu!micro-heart-of-gold.mit.edu!bloom-beacon.mit.edu!bloom-beacon.mit.edu!panix!panix.com!forkosh From: JohnF Newsgroups: comp.lang.postscript Subject: Re: hypercube rotations Date: Sat, 16 Jul 2016 00:14:09 +0000 (UTC) Organization: PANIX Public Access Internet and UNIX, NYC Lines: 37 Message-ID: References: <46e56073-6c7b-416e-8733-a2fe836c3a71@googlegroups.com> NNTP-Posting-Host: panix3.panix.com X-Trace: reader1.panix.com 1468628049 13539 166.84.1.3 (16 Jul 2016 00:14:09 GMT) X-Complaints-To: abuse@panix.com NNTP-Posting-Date: Sat, 16 Jul 2016 00:14:09 +0000 (UTC) User-Agent: tin/1.6.2-20030910 ("Pabbay") (UNIX) (NetBSD/6.1.5 (i386)) Xref: csiph.com comp.lang.postscript:2703 Peter Billam wrote: > On 2016-07-08, luser droog wrote: >> A year or two ago I tried to beef-up my vector analysis skills >> by reading the very interesting History of Vector Analysis. >> I can now spell Ausdehnungslehre, but I never figured out how >> to do a Grassman product. Quaterions freak me out. For that >> matter, the complex plane still freaks me out. I think I need >> to take a math class. > > The most helpful intro to Grassman products I know is > Roger Penrose "The Road To Reality" pp.211-215, 227-229. > He's a great explainer, but it's a heavy book, 1094 pages... > Not that I've ever actually _used_ a Grassman product :-) > The complex plane is not scary, in fact Roger Penrose mostly > exists in the complex plane. He introduces it in pp.81-83,87-88... That's a terrific book, uniquely filling an otherwise empty niche, introducing a lot of significant "mathematics for physicists" for readers without all the usual prerequisites. You do need enough background so as not to get scared just looking at math, but then you come away really knowing some stuff. (Sometimes I find him a bit too wordy with tangential prose, unnecessarily interrupting the main stream of concepts to the point you can lose track of what you were doing.) > Wikipedia is really authoritative in this kind of thing, > but it's often overwhelming, and > https://en.wikipedia.org/wiki/Exterior_algebra > is a example of that :-( Regards, Peter > P.S. I've never used a quaternion either, and mainly know them from > http://math.ucr.edu/home/baez/octonions/ > by John C. Baez He's done some really good work, too, and put up a lot of good stuff on the web. Two nice references, pjb. -- John Forkosh ( mailto: j@f.com where j=john and f=forkosh )