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From: Jim Lambaugh on 11 May 2010 06:24
Hi guys

I have a function f(x), and I need to find its discrete Fourier
transform. I have taken a look at http://reference.wolfram.com/mathematica/tutorial/FourierTransforms.html,
but it only returns the amplitude of the FT. - not the phase factor.
Which command do I have to use in order to get the phase factor as
well?

Best,
Jim.

From: Niles on 12 May 2010 07:32
On 11 Maj, 12:24, Jim Lambaugh <lamba...(a)gmail.com> wrote:
> Hi guys
>
> I have a function f(x), and I need to find its discrete Fourier
> transform. I have taken a look athttp://reference.wolfram.com/mathematica/tutorial/FourierTransforms.html,
> but it only returns the amplitude of the FT. - not the phase factor.
> Which command do I have to use in order to get the phase factor as
> well?
>
> Best,
> Jim.

I'm not quite sure; I had to use this function as well some time ago,
but I never resolved the issue.

From: Nasser M. Abbasi on 12 May 2010 07:32

"Jim Lambaugh" <lambaugh(a)gmail.com> wrote in message
news:hsbb96$jdt$1(a)smc.vnet.net...
> Hi guys
>
> I have a function f(x), and I need to find its discrete Fourier
> transform. I have taken a look at
> http://reference.wolfram.com/mathematica/tutorial/FourierTransforms.html,
> but it only returns the amplitude of the FT. - not the phase factor.
> Which command do I have to use in order to get the phase factor as
> well?
>
> Best,
> Jim.
>

DFT takes as input a list of numbers (not a function f(x)) and returns a
list of numbers.

DFT does not return "just the amplitude of the FT", where does it say that?
in the documentation? if it does, need to report it to WRI because that
would be an error in documentation.

To find the "amplitude" of a complex number v, use the command Abs[v], to
find its "phase", use Arg[v]

--Nasser



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