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Re: How to find Complex roots !!

• To: mathgroup at smc.vnet.net
• Subject: [mg25992] Re: [mg25952] How to find Complex roots !!
• From: Daniel Lichtblau <danl at wolfram.com>
• Date: Wed, 15 Nov 2000 02:09:43 -0500 (EST)
• References: <200011140846.DAA27197@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

jncheong wrote:
> 
> I'd like to know how to find complex roots in the equation like:
> 
> f(x) = x^n + x^(n-1)+ ...+ x*cos(x)*i+ x*cosh(x) *i + something=0;
> 
> Please let me know if any  using mathematica.


One way would be to use FindRoot.

In[24]:= f = x^5+x^4+x^3+x^2+x+x*Cos[x]*I+x*Cosh[x]*I+5;

In[25]:= FindRoot[f==0, {x,1+I}]

Out[25]= {x -> 0.711602 + 1.01295 I}

In[26]:= f /. %

                  -13             -13
Out[26]= 1.2812 10    + 1.11522 10    I


Daniel Lichtblau
Wolfram Research

• References:
  • How to find Complex roots !!
    • From: "jncheong" <jncheong@postech.ac.kr>