Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!rex!ukma!dftsrv!mimsy!coredump.umiacs.umd.edu!peyote From: peyote@coredump.umiacs.umd.edu (Gary Flake) Newsgroups: comp.theory Subject: Re: Question on halting problem Keywords: for 10 bonus points... Message-ID: <33639@mimsy.umd.edu> Date: 27 Apr 91 03:09:14 GMT References: <1991Apr26.135918.8607@m.cs.uiuc.edu> Sender: news@mimsy.umd.edu Organization: UMIACS, Univ. of Maryland, College Park, MD 20742 Lines: 29 I'll give this a try. One assumption: I get a floating point representaion such that the mantissa grows as needed for precision, not to exceed linear growth, so a TM can handle this as well. logistic_map() { float start = 0.72683747835872456784398234476582; float end = 0.38947584759487534985798237949835; while (start != end) start = 3.9 * start * (1.0 - start); } As a discrete chaotic system, the above will *probably* not repeat itself, but the point is that you can't know without running the beast. Why the 3.9 (instead of 4.0) ? Ulam came up with an analytical solution for 4.0, so I thought that we'd add some more ugliness to the function. 3.9 is still within the chaotic regime. Extra credit for brevity? Gary Flake. ------ peyote@umiacs.umd.edu