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MathGroup Archive 2002

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FourierTransform Problem again

  • To: mathgroup at smc.vnet.net
  • Subject: [mg35160] FourierTransform Problem again
  • From: David Turner <dturner at faulkner.edu>
  • Date: Thu, 27 Jun 2002 00:23:27 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

Hello,

I received several replies to my FourierTransform problem (see below).  Some
involved replacing := with =.  Some others involved using Evaluate[].
However, each of these suggestions led to the same error messages.  Other
people indicated I should upgrade to version 4.1.  However, I already use
version 4.1 under another license and I knew my code below evaluated
correctly with 4.1.  I still sometimes use version 3.0 because some packages
I have do not always work correctly with version 4.1 but work well with
version 3.0 (for example, the excellent ExtendGraphics package by Tom
Wickham-Jones).  This problem with FourierTransform under 3.0 arose about 4
years ago when I was taking my undergraduate quantum mechanics class.  A
particular homework assignment in that class involved evaluating and
graphing some inverse fourier transforms.  Myself and other students in that
class encountered the same error messages I list below on the university
computers.  Our professor apparently did not have this problem since he had
the corrected FourierTransform.m for 3.0 on the computer in his office.  I
contacted mathematica technical support.  They replied with an ftp site
where the corrected FourierTransform package might be downloaded.  After
doing so, we were able to correctly evaluate the problems on that
assignment.  I lost my copy of the corrected FourierTransform package when
my old laptop died.

So, does anyone have a copy of FourierTransform.m for 3.0 more recent than
7/21/97 that I might have, or could anyone give me an address where I might
download a more recent copy which works with 3.0?

Thanks.

David

Original message:

I am using Mathematica for Students 3.0.1 with Windows 98.  When I execute
the following code, I get the error messages below:

In[1]:=  <<Calculus`FourierTransform`

In[2]:=  Clear[fx, fw, a]

In[3]:=  a:=1

In[4]:=  fx[x_]:=Exp[-Abs[x*a]]

In[5]:=  fw[w_]:=InverseFourierTransform[fx[x], x, w]

In[6]:=  Plot[fw[w], {w, -5*a,5*a}]

Plot::plnr : fw[w] is not a machine-size real number at w = -5..
Plot::plnr : fw[w] is not a machine-size real number at w = -4.59433..
Plot::plnr : fw[w] is not a machine-size real number at w = -4.15191..
General:: stop : Further output of Plot::plnr will be suppressed
during this calculation.

Does anyone know where I might obtain a corrected FourierTransform.m package
for Mathematica 3.0.1?  My copy is dated 7/21/97.  I contacted Wolfram
about this matter.  However, they told me they no longer support version
3.0.  I appreciate any help you may provide.


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