Path: news.mathworks.com!not-for-mail
From: "Michael Snyder" <sirzerp@mathworks.com>
Newsgroups: comp.soft-sys.matlab
Subject: Re: algebraic problem, no explicit solution
Date: Tue, 19 Feb 2008 15:49:03 +0000 (UTC)
Organization: Murray State Univeristy
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Thank you Mr. Stafford.

I'm working on it today.  Yes I am using CAS.  Both Matlab
and Maple.

Want to see something funny?  Type this command into Maple.


>
solvefor[y](1/k=1/((x-x1)^2+(y-y1)^2+(z-z1)^2)^(1/2)-1/((x-x2)^2+(y-y2)^2+(z-z2)^2)^(1/2));

y =
(-2*x*x1+x1^2+y1^2-2*z*z1+z1^2+2*x*x2-x2^2-y2^2+2*z*z2-z2^2+2*k*Root\
Of(4*x^2*y2^2-4*y1*z2^2*y2-4*x*x1*z1^2+4*y1^2*x^2-8*x^2*y2*y1-8*y1*z^2*y\
2-4*y1*x2^2*y2-4*z1^2*y2*y1+4*x^2*x2^2-8*z*z1*x*x2+2*x1^2*y2^2-4*x*x1*y1\
^2-4*x1^2*y2*y1-8*x*x1*z*z2+8*z*z1*y2*y1-4*_Z^7*k^3+(-24*z1^3*k^2*z+12*x\
...

You will get 41 pages of result with 25 rootof causes.

Trying to solve a single line well known equation produces
41 pages!  That probably is why Matlab didn't return a result.  

BTW, I believe I want the complex roots.  I'm writing a
paper, and some of it deals with the complex plane.    

Thanks again,

Michael Snyder

> 
> to eliminate false solutions, as well as discarding the
complex-valued ones.
> 
> Roger Stafford
>