Re: Re: Harmonic Analysis
- To: mathgroup at smc.vnet.net
- Subject: [mg25626] Re: [mg25601] Re: [mg25591] Harmonic Analysis
- From: Roberto Brambilla <rlbrambilla at cesi.it>
- Date: Mon, 16 Oct 2000 03:04:46 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
My idea is to use Coefficient : given
expr = a00 + a10 f[t] + a01 g[t] + a11 f[t] g[t]+
a20 f[t]^2 + a21 f[t]^2 g[t] //Expand;
f[t] = f1 Exp[+j w t] + f1Star Exp[-j w t]
g[t] = g1 Exp[+j w t] + g1Star Exp[-j w t]
I extract exponential coefficient in this way :
(n=-3,-2,-1,1,2,3)
In[..] n=1; Coefficient[expr, Exp[n j w t]]
Out[..] a10 f1 + a01 g1 + 2 a21 f1 f1Star g1 + a21 f1^2 g1Star
In[..] n=-2; Coefficient[expr, Exp[n j w t]]
Out[..] a20 f1Star^2 + a11 f1Star g1Star
Unfortunately it does not work for n=0
Bye, Rob
Roberto Brambilla
CESI
Via Rubattino 54
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tel +39.2.2125.5875
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rlbrambilla at cesi.it