### Notation and Terminology

If is the DFT of , we say that and form a *transform
pair* and write

If we need to indicate the length of the DFT explicitly, we will write
and
.
As we've already seen, *time-domain* signals are consistently denoted
using *lowercase* symbols such as ``,'' while *frequency-domain*
signals (spectra), are denoted in *uppercase* (``
'').

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