
Re: Linear Algebra Question
Posted:
Apr 16, 2014 10:30 AM


On Tue, 15 Apr 2014 16:40:31 0700 (PDT), federation2005@netzero.com wrote:
>On Sunday, April 13, 2014 11:25:51 AM UTC5, dull...@sprynet.com wrote: >> Just realized I've been lying to my students for years. >> Q. Say A is a 2x2 real matrix, b is in R^2 and b <> 0. >> Let S = {x in R^2 : Ax = b}. Is S closed under addition? >> A: ??? > >Perhaps you're unaware of how ordinary you (and this) are. Even texts and monographs are filled with errors of this sort and worse (even dictionaries!)
Or who knows, maybe I _am_ aware of that. Maybe I pointed out that I'd got this wrong in class many times for a reason.
Who knows?
>The worst of the lot, when it comes to math and science publishing, is Cambridge University Press (out of England) whose monographs are frequently filled with whoppers of errors (e.g. a definitive reference on exact solutions in general relativity, considered the bible of the subject by many, giving the wrong formula for the Riemann curvature tensor(!) and a completely wrong account of what a Lie derivative is(!!); other examples cover fields in math, comp. sci. as well).

