Perusjaksoja
Perusjaksoja is the plural form of perusjakso, a Finnish term meaning fundamental period or base period. In mathematics and physics, perusjakso refers to the smallest positive interval T over which a periodic function repeats, so that f(t + T) = f(t) for all t in its domain. If such a smallest T exists, it is the fundamental period; any other period of the function is a multiple of T. In discrete-time contexts, for a sequence x[n], the fundamental period N is the smallest positive integer with x[n + N] = x[n] for all n.
The concept is central to analyses that rely on repeating behavior, such as Fourier analysis, spectral decomposition,
Examples: sin(t) has fundamental period 2π in continuous time. A square wave with period T has the
Notes: The term is common in Finnish technical literature dealing with periodic phenomena, waves, and harmonic