Programmer Guide/Command Reference/EVAL/dft: Difference between revisions
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|complex spectrum with N/2+1 values | |complex spectrum with N/2+1 values | ||
|N+2 | |N+2 | ||
|<code>real->complex</code> | |forward <code>real->complex</code> dft<BR>note: only the first half (values: 0..N/2) of the conj. sym. complex spectrum is stored in ''y'' | ||
|- | |- | ||
|'''1''' | |'''1''' | ||
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|complex spectrum with N values | |complex spectrum with N values | ||
|2N | |2N | ||
|<code>complex->complex</code> | |forward <code>complex->complex</code> dft | ||
|- | |- | ||
|'''2''' | |'''2''' | ||
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|real signal with N samples | |real signal with N samples | ||
|N | |N | ||
|<code>complex->real</code> | |inverse <code>complex->real</code> dft<BR>note: the inverse of ''type''=0 | ||
|- | |- | ||
|'''3''' | |'''3''' | ||
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|complex signal with N samples | |complex signal with N samples | ||
|2N | |2N | ||
|<code>complex->complex</code> | |inverse <code>complex->complex</code> dft | ||
|- | |- | ||
|} | |} | ||
Revision as of 12:03, 12 April 2011
Inverse or forward discrete fourier transform (dft).
- Usage
dft(x {, type)- xthe data vector to be transformed
- type
- selects the data type of the argument and result and the transformation to be performed (default=0)
- Result
- A vector y containing the result of the transformation. The length and content of y depends on x and type.
type x nrow(x) y nrow(y) description 0 real signal with N samples N complex spectrum with N/2+1 values N+2 forward real->complexdft
note: only the first half (values: 0..N/2) of the conj. sym. complex spectrum is stored in y1 complex signal with N samples 2N complex spectrum with N values 2N forward complex->complexdft2 first half (values: 0..N/2) of a conj. sym. complex spectrum N+2 real signal with N samples N inverse complex->realdft
note: the inverse of type=03 complex spectrum with N values 2N complex signal with N samples 2N inverse complex->complexdft
