| Author |
Comment/Response |
Edoardo
|
 10/24/06 11:39am
Helloeverybody, I 've a general question on a DFT problem, solved with the Fourier[] command.
Given for example 32 data (real numbers) and asked the program to compute Fourier, I got 32 complex vector, and that is ok.
Actually 2 of these vectors are real, the other are 15 complex (and the relative conjugates). That is also ok.
Then, I want to 'translate' the complex in to 16 armonic functions, terms such as A*cos[freq*t+phase].
So I ask the program for the amplitudes (command Abs) and for the phase (command Arg) and combine them with the above written formula.
I know that the term relative to frequency =0 is the first one, then the problem is: the term relative to the first armonic I am considering (the one with lower frequency, Pi/16 in this case) is the second one or the last (in the vector of teh complex numbers)?
I have the feeling that mathematica is putting the vector in a wired order, also because doing the same stuff with other programs I got the same complex vectors, but in a different order.
Does any of you an idea of what is going on about it?
Thanks
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