FourierTransform
- To: mathgroup at smc.vnet.net
- Subject: [mg24546] FourierTransform
- From: "Rasmus Debitsch" <debitsch at Zeiss.de>
- Date: Mon, 24 Jul 2000 03:04:25 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
Hello MathGroup,
I'm trying to compute the Fourier transform of cos[a + t] and get the result
0 :
Clear[a, t, s];
FourierTransform[Sin[t + a], t, s]
Out[67]= 0
Splitting the expression and computing the single terms gives :
In[68]:= Sin[t + a] // TrigExpand
Out[68]= Cos[t] Sin[a] + Cos[a] Sin[t]
In[69]:= Clear[a, t, s];
FourierTransform[Cos[t] Sin[b], t, s] +
FourierTransform[Cos[b] Sin[t], t, s]
Out[70]= Cos[b]*(I*Sqrt[Pi/2]*DiracDelta[s - 1] -
I*Sqrt[Pi/2]*DiracDelta[s + 1]) +
(Sqrt[Pi/2]*DiracDelta[s - 1] +
Sqrt[Pi/2]*DiracDelta[s + 1])*Sin[b]
which is the expected result. What's wrong with my first try ?
Regards
Rasmus
--
Rasmus Debitsch
Carl Zeiss Lithos GmbH
Carl Zeiss Strasse
D-73447 Oberkochen
eMail : debitsch at zeiss.de