Path: news.mathworks.com!not-for-mail From: <HIDDEN> Newsgroups: comp.soft-sys.matlab Subject: Re: fix point iteration Date: Sat, 25 Apr 2009 19:11:01 +0000 (UTC) Organization: The MathWorks, Inc. Lines: 14 Message-ID: <gsvn85$60m$1@fred.mathworks.com> References: <gsvhnt$gmt$1@fred.mathworks.com> Reply-To: <HIDDEN> NNTP-Posting-Host: webapp-02-blr.mathworks.com Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 8bit X-Trace: fred.mathworks.com 1240686661 6166 172.30.248.37 (25 Apr 2009 19:11:01 GMT) X-Complaints-To: news@mathworks.com NNTP-Posting-Date: Sat, 25 Apr 2009 19:11:01 +0000 (UTC) X-Newsreader: MATLAB Central Newsreader 1187260 Xref: news.mathworks.com comp.soft-sys.matlab:535434 "Yi" <hvachy@163.com> wrote in message <gsvhnt$gmt$1@fred.mathworks.com>... > I want to plot a curve, x is my independent value, and y is the dependent value. > But I have > y = f1(a,b,x) > a = g1(a,b,x) > b = g2(a,b,x) > I want to assume the x value in a reasonable interval and then use fix point iteration to solve a and b first, using function a and b. Then drive these a and b and x(assumption) into y and then plot the curve. > I don't know how to solve a and b. Which command should I use? Fixed point iteration is a very general concept for solving equations. It is necessary to choose an appropriate formula/method for carrying out the iteration, as for example the Newton-Raphson method or Halley's method. In your case you need a two-variable method. See the Wikipedia article at: http://en.wikipedia.org/wiki/Fixed_point_iteration Roger Stafford