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MathGroup Archive 2005

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Re: Mathematica for Summation of Trigonometry expression

  • To: mathgroup at smc.vnet.net
  • Subject: [mg54012] Re: Mathematica for Summation of Trigonometry expression
  • From: Roland Franzius <roland.franzius at uos.de>
  • Date: Mon, 7 Feb 2005 03:13:03 -0500 (EST)
  • Organization: Universitaet Hannover
  • References: <cu21s0$m5d$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

cheanglong at gmail.com wrote:
> Dear All Mathematica user
> 
> Im trying to use Mathematica for Summation of Trigonometry
> expression..... but it can't be evaluated as I think the expression is
> too BIG or LONG.
> 
> I think it must be simplified further before evaluated in mathematica.
> Kindly give me your opinion. please
> 
> The summation has to be done for the below expression from n=1 to n=126
> 
>   expression1=>   A.cos(w+ i.delta)t from i=1,2,3... to i=N=126
> 
> A is amplitude, w angular frequency, delta is just a spacing/interval,
> t is time of course. This is a typical sinusoidal signal.
> 
> But to find the summation for all the terms from i=1 to i=126,
> I need to have maybe a simplified power series to be evaluated in
> mathematica? or ? I dont know, as
> mathematica cant find the answers.
> 
> Kindly help me . Thank you so much in advance
> Wish to hear from you all
Set e^( I w) -> u,  e^(I i delta ) ->q  and
cos[w + i delta]-> 1/(2 I) (e^(I w) e^(I i delta) + e^(-I w) e^(-I i 
delta) 	 )

This gives you some geometric sums easy to sum by inspetion. No 
Mathematica tool will help you for such an easy complex calculation. But 
you can use Mathematica to check the result.

--

Roland Franzius


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