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Re: Creation and evaluation of polynomials

  • To: mathgroup at smc.vnet.net
  • Subject: [mg89453] Re: Creation and evaluation of polynomials
  • From: dh <dh at metrohm.ch>
  • Date: Tue, 10 Jun 2008 03:39:00 -0400 (EDT)
  • References: <g2j05j$510$1@smc.vnet.net>


Hi,

could you please explain how {1,0,0,0,1,0,1} is related to p^5 + 3p^2? 

Perhaps, you mean {0, 0, 3, 0, 0, 1}, what I could understand. If so, 

there is no need to convert to a string:

p={0,0,3,0,0,1};

pol[p_,var_]:= p.Table[var^i,{i,0,Length[p]-1}];

pol[p,x]

hope this helps, Daniel



jmgomezgoo at gmail.com wrote:

> Hi!

> 

> Image we have a function that create a Polynomial:

> 

> polynomial[{1,0,0,0,1,0,1,}] -> p^5 + 3p^2

> 

> And we want to calulate roots and the derivate of this polynomial.

> 

> I try with ToString[polynomial[{1,0,0,0,1,0,1}]] in order to use

> convert the polynomial expression to string first and later use

> 

> ToExpression[]

> 

> and calculate roots

> 

> D[ToExpression[ToString[polynomial[{1,0,0,0,1,0,1}]], x]

> 

> like the next examples:

> 

> D[ToExpression["x^2+2x"], x]

> 

> or

> 

> NSolve[ToExpression["x^2+2x==x"], x]

> 

> 

> But ToString erase ^ symbol.

> 

> Somebody knows how to solve it?

> 

> 

> Warm regards

> -jm

> 

> 

> 





-- 



Daniel Huber

Metrohm Ltd.

Oberdorfstr. 68

CH-9100 Herisau

Tel. +41 71 353 8585, Fax +41 71 353 8907

E-Mail:<mailto:dh at metrohm.com>

Internet:<http://www.metrohm.com>




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