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