Path: news.mathworks.com!not-for-mail From: <HIDDEN> Newsgroups: comp.soft-sys.matlab Subject: Re: need complex roots Date: Thu, 8 Jan 2009 18:13:02 +0000 (UTC) Organization: The MathWorks, Inc. Lines: 26 Message-ID: <gk5fne$ggo$1@fred.mathworks.com> References: <gk5cee$bt5$1@fred.mathworks.com> <gk5e8h$cgs$1@fred.mathworks.com> Reply-To: <HIDDEN> NNTP-Posting-Host: webapp-05-blr.mathworks.com Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 8bit X-Trace: fred.mathworks.com 1231438382 16920 172.30.248.35 (8 Jan 2009 18:13:02 GMT) X-Complaints-To: news@mathworks.com NNTP-Posting-Date: Thu, 8 Jan 2009 18:13:02 +0000 (UTC) X-Newsreader: MATLAB Central Newsreader 1187260 Xref: news.mathworks.com comp.soft-sys.matlab:510479 "Roger Stafford" <ellieandrogerxyzzy@mindspring.com.invalid> wrote in message <gk5e8h$cgs$1@fred.mathworks.com>... > "Ramesh Kudenatti" <ramesh@bub.ernet.in> wrote in message <gk5cee$bt5$1@fred.mathworks.com>... > > Hi > > Could anyone tell me how to find the roots of equation involving the transcendental functions like Airy function and its derivative with complex argument? My function is given below. > > AiryAiPrime(Z)-c1 Exp[I Pi/6] ==0 where Z = I W (6 I k)^(-2/3), W is unknown, c1 and k are known. > > > > Requesting.......... > > For using 'fsolve' to find complex roots see the recent discussion of this problem at: > > "finding complex root from nonlinear equations" > http://www.mathworks.com/matlabcentral/newsreader/view_thread/241861 > > Roger Stafford My apologies! I hadn't noticed until now that you participated in that thread yourself, Ramesh. The only additional thing I can think of suggesting is that you first find the complex roots Z in AiryAiPrime(Z) = c1*exp{pi/6*i) using 'fsolve'. After that you can solve Z = i*W*(6*k*i)^(-2/3) for W by W = Z*(6*k)^(2/3)*i^(-1/3) which has three trivially easy roots for each Z root found. This will perhaps make things easier for using 'fsolve' by reducing the number of roots for it to find. Roger Stafford