DFT Definition
The
Discrete Fourier Transform (DFT) of a
signal 
may be defined by

where `

' means ``is defined as'' or ``equals by definition'', and
The
sampling interval 
is also called the
sampling period.
For a tutorial on sampling continuous-time signals to obtain
non-
aliased discrete-time signals, see Appendix
D.
When all

signal samples

are real, we say

.
If they may be complex, we write

. Finally,

means

is any integer.
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