threeperiod

Threeperiod is a term used to describe a structure or sequence that repeats every three units. The term is informal and appears in discussions of tri-periodic patterns across mathematics and related disciplines.

In mathematics, a sequence (a_n) is three-periodic if a_{n+3} = a_n for all integers n. An example is 5, 9, 2, 5, 9, 2, ... Here the pattern repeats every three terms. Three-periodicity is a special case of general periodicity and may also imply smaller periods in constant sequences.

In data analysis and signal processing, threeperiod can describe signals or time series with a triadic repeating pattern. It is often used as a descriptive shorthand rather than a formal category.

Etymology: The term combines "three" and "period" to reflect the repeat length of three.

See also: Periodic sequence; Triplet pattern; Tri-periodic; Discrete time signal.