> Hiroyuki Kawakatsu
> on Thu, 5 Feb 2015 12:40:28 + writes:
> On 2015-02-05 Martin Maechler wrote:
> [...]
>> Both a definition of the DFT (in LaTeX or directly as \deqn{}{}) which
>> matches *our* fft(), and an extended commented example (ca 20 lines,
>> rath
On 2015-02-05 Martin Maechler wrote:
[...]
> Both a definition of the DFT (in LaTeX or directly as \deqn{}{}) which
> matches *our* fft(), and an extended commented example (ca 20 lines,
> rather than ca 100 lines!) would be welcome additions.
[...]
Here is a previous attempt:
https://stat.ethz.
Dear Jeff, Franklin, Eike and other interested parties,
I agree that the help page for fft() deserves a bit more detail;
its source is
https://svn.r-project.org/R/trunk/src/library/stats/man/fft.Rd
For instance, it has the comment
%%
%% Here, we should really have a nice \deqn{}{} giving t
I see now the trick... the square wave clarified it for me. It is indeed
faster than re-arranging the data if putting the zero frequency in the
middle of the data is your goal.
Since I only do that for the purposes of teaching I probably won't be
using it, but it may well be an interesting "tr
Dear Elke; Jeff,
Re:
> Eike: Understanding Discrete Fourier Transform theory is not trivial... while
> a vignette added to the stat package has the potential help a lot of users,
> it is a bit ambitious to try to supplant the extensive published material on
> using and interpreting the DFT (p
Eike: Understanding Discrete Fourier Transform theory is not trivial...
while a vignette added to the stat package has the potential help a lot of
users, it is a bit ambitious to try to supplant the extensive published
material on using and interpreting the DFT (particularly as there is "more
t
Dear Frank,
thanks a lot for your reply. I was aware of the need for FFT normalization and
folding, but you're making another good point here, stating that there should be
examples on this (folding) in the documentation as it will pose quite an
obstacle for newcomers attempting to practically use
Dear Eike Petersen,
Re:
> Hello everyone,
>
> the docpage for the fft function states:
>
> “Description: Performs the Fast Fourier Transform of an array.”
>
> and
>
> “Arguments – inverse: if ‘TRUE’, the unnormalized inverse transform is
> computed
> (the inverse has a ‘+’ in the exponent o
Hello everyone,
the docpage for the fft function states:
“Description: Performs the Fast Fourier Transform of an array.”
and
“Arguments – inverse: if ‘TRUE’, the unnormalized inverse transform is computed
(the inverse has a ‘+’ in the exponent of e, but here, we do _not_ divide by
‘1/length(x)’
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