Plotting the complex fft in 3D?
Just another remakr on this thread. I you have time series and think about its fourier transform (EE language) then you should know that the statistical language of that is "spectral analysis" or maybe "frequency domain time-series analysis" and the R function to consider should definitely be spectrum() which is a wrapper (among others) to spec.pgram() -- which calls fft() -- for computing the so-called "periodogram". If you learn more about the topic, you will learn that in almost all cases you'd consider a *smoothed* version of the periodogram, etc etc (because the so-called *raw* periodgram is *in*consistent as an estimate fo the underlying true spectrum). The Time-Series chapter/section of the MASS book is very helpful here, IIRC. Martin Maechler, ETH Zurich
"OB" == Oliver Bandel <oliver at first.in-berlin.de>
on Thu, 4 Sep 2008 23:16:07 +0200 writes:
OB> Zitat von Duncan Murdoch <murdoch at stats.uwo.ca>:
>> On 04/09/2008 4:44 PM, Oliver Bandel wrote:
>> > Zitat von Duncan Murdoch <murdoch at stats.uwo.ca>:
>> >
>> >> Oliver Bandel wrote:
>> >>> Hello,
>> >>>
>> >>>
OB> [...]
>> plot3d doesn't support that directly, but you could plot with
>> type='n',
>> then use segments3d to add the lines.
>>
>> >
>> > BTW: how to change the perspective? I did not found an
>> > angle-parameter for the plot3d()-function.
>>
>> Just grab it with your mouse and drag.
OB> Wow, coool! :-)
OB> Well, rgl.... I think "gl" stands for OpenGl.
OB> Fine. :-)
>> Alternatively,
>> play3d(spin3d())
>> will spin it, or par3d(userMatrix=rotationMatrix(...)) for a fixed
>> setting.
OB> Ok, some thinsg to play with.
OB> Thank you.
OB> Ciao,
OB> Oliver
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