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MathGroup Archive 2003

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Emergent Help: NSolve Problems!

  • To: mathgroup at smc.vnet.net
  • Subject: [mg39753] Emergent Help: NSolve Problems!
  • From: Chengzhou Wang <wcz at ece.ucsd.edu>
  • Date: Thu, 6 Mar 2003 02:35:04 -0500 (EST)
  • Sender: owner-wri-mathgroup at wolfram.com

Hi, guys

I have some complicated polynomials, and I want to calculate its roots.
HOwever, when I use NSolve, it creates some problems. Say a simple
example:

temp[s_]=s^10+10 s^9+ 10 s^8 +10 s^7 +10 s^6+ 10 s^5 +10 s^4 +1; 
NSolve[temp[s]==0, s]

It will give:

Out[4]= {{s -> -8.99998}, {s -> -1.06539}, {s -> -0.468828 - 0.886239 I}, 
 
>    {s -> -0.468828 + 0.886239 I}, {s -> -0.409684 - 0.469948 I}, 
 
>    {s -> -0.409684 + 0.469948 I}, {s -> 0.401048 - 0.312597 I}, 
 
>    {s -> 0.401048 + 0.312597 I}, {s -> 0.51015 - 0.878693 I}, 
 
>    {s -> 0.51015 + 0.878693 I}}

But when I plug in the first number, which is "-8.99998", it should give a
value close to zero. However, it gives:

In[5]:= temp[-8.99998]
Out[5]= -411.473

The other roots seems OK. Does anyone know why? This is just a simple
example. I have some more complicated polynomials to deal with. 

Thanks in advance!

PS: Please reply (cc) to my email. I did not subscribe my email to the
this email group!

--
Chengzhou



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