Re: fourier transforms
- To: mathgroup at smc.vnet.net
- Subject: [mg17511] Re: fourier transforms
- From: Hendrik van Hees <h.vanhees at gsi.de>
- Date: Mon, 10 May 1999 19:53:17 -0400
- Organization: GSI Darmstadt
- References: <7grgk2$e3i@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
lucas wrote:
>
> hello,
>
> i am trying to do some fourier transforms with mathematica 3.0. i does
> not behave as i expect, but perhaps i expect too much or do not
> understand enough of mathematica. anyway, check this out.
>
> f[x] = Exp[-m x]
>
> <<Calculus`FourierTransform`
>
> FourierCosTransform[f[x],x,a]
>
> is supposed to return
>
> m/(m^2 + a^2) when m > 0
>
> but instead it returns the original FourierCosTransform[E^(-m x),x,a],
> which any dummy can figure out.
>
[...]
My session of Mathematica 3.0 for your problem gives
===============================================================
In[1]:= <<Calculus`FourierTransform`
In[2]:= In[2]:=
In[2]:= f[x_]=Exp[-m*x]
-(m x)
Out[2]= E
In[4]:= FourierCosTransform[f[x],x,a]
m
Out[4]= -------
2 2
a + m
===============================================================
My system (although Mathematica is claimed to be independent of the
system) is an intel Celeron 233 running Linux 2.2.5 and Mathematica 3.0
for students.
It might be the problem that you have forgotten the underscore in the
definition of the orginal function f!
--
Hendrik van Hees Phone: ++49 06159 71-2755
c/o GSI-Darmstadt SB 3.162 Fax: ++49 06159 71-2990
Planckstr. 1 mailto:h.vanhees at gsi.de
D-64291 Darmstadt http://theory.gsi.de/~vanhees/vanhees.html