
Re: Linear Algebra Question
Posted:
Apr 15, 2014 7:40 PM


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!) 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).

