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Harmonic analysis is used to identify the periodic (regular)
variations in
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geophysical time series.
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If we have N observations of (xi,
yi), the time series y(t)
can be
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approximated by cosine and sine functions :
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How many harmonics (cosine/sine functions) do we
need?
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In general, if the
number of observations is N, the number of harmonic
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equal to N/2 (pairs of cosine and sine functions).
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