Solve / NSolve take too much time or fail

• To: mathgroup at smc.vnet.net
• Subject: [mg60847] Solve / NSolve take too much time or fail
• From: "grimey" <tfgeyer at yahoo.com>
• Date: Fri, 30 Sep 2005 03:57:14 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

```Hello,
I'm working with Mathematica (version 5.0) for perhaps 3 month.
And now I have a problem, I try to solve an equation like this:

cf=(a1*x (a2 + a3*x + a^2))/(b1 + b2*x - b3*x^2 + b4*x^3);

w=(1-c1*Sqrt[1-(1-c1^2)*x/c2])^2 / (1-c1)^2;

This is the main equation:

Solve[Numerator[cf]-I d1 w Denominator[cf]==0,x]

And even after hours of working I don't get any solution, whether I
take Solve or NSolve. And I gave a lot of virtual memory free for
Mathematica to work with.

Are there any tricks to help solving difficult polynomial equations
faster (or at all)? I want to get, of course, a set of Root-functions
for x (complex), depending on a1, a2, a3, b1, b2, b3, b4, c1, c2, d1,
so I have no numerical number to start with for the FindRoot-function.
Can anyone help me? Some other equations, not always that different
from this one, could be solved more easily...

Thank you very much!

Thomas Geyer
(tfgeyer at yahoo.com)

```

• Prev by Date: Re: Sorting Strings: How and Why so f\$&!ing hard?
• Next by Date: Re: nonlinear fit question
• Previous by thread: Re: axes for Plot3D
• Next by thread: simultaneous ... and ___