If *f* is sampled at time *t*_{i} we are left with
(*f*_{i},*t*_{i}) , where *N* is the total number
of measurements. In the frequency domain,
Deeming (1975, 1976) showed how the irregular discretization
affects the power spectrum : the spectrum results
from the convolution between the real spectrum and the
spectral window . is the Fourier
transform of . That is
.

We can state the result as follows.
Let^{} *p* be the largest value such that ,, where
. *p* is
a kind of greatest common divisor (gcd) for all (*t*_{i}-*t _{1}*).
The Nyquist frequency then is:

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