Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!apple!agate!agate!hughes From: hughes@maelstrom.Berkeley.EDU (Eric Hughes) Newsgroups: comp.windows.ms.programmer Subject: Re: Actor: bad numerical precision? Message-ID: Date: 5 Dec 90 15:23:45 GMT References: <20060@rouge.usl.edu> Sender: usenet@agate.berkeley.edu (USENET Administrator) Followup-To: sci.math.num-analysis Organization: ucb Lines: 21 In-Reply-To: pcb@cacs.usl.edu's message of 5 Dec 90 05:22:54 GMT This question is really about numerical analysis, not Actor, and even less Windows. In article <20060@rouge.usl.edu> pcb@cacs.usl.edu (Peter C. Bahrs) writes: >I just wrote an inverse method for a matrix class using simple row >reduction. > [gets non-zero values off-axis] >???What gives, I am confident the algorithm is correct. It works most >of the time. But this is a terrible error factor here that will build >up in time. Is Actor weak in numerical precison? No more so than all computers are. Simple row-reduction schemes do not work well in all cases when the determinant of the matrix is very close to zero. The round-off errors become significant and large. Ask this same question in sci.math.num-analysis. It's a basic question. Eric Hughes hughes@ocf.berkeley.edu