The Shannon sampling theorem [1, 4, 5] states that a continuous function
can be reconstructed, without error, from evenly spaced sample points, provided
that two criteria are met. First the function must be band-limited. That means
that its Fourier spectrum is zero for all frequencies above some cutoff frequency,
which we call f
c
. This means the function can have no sinusoidal components of
frequency greater than f
c
. Second, the sample spacing must be no larger than
Dx ¼ 1=2f
c
. This means there will be at least two sample points per cycle of the
highest-frequency sinusoidal component of the function. If these two criteria are
met, the function can be recovered from its samples by the process of interpol-
ation, if that is properly done.
If Dx < 1=