periodisch

Periodisch is an adjective describing something that occurs or repeats at regular intervals or with a fixed period. The term is used across disciplines such as mathematics, physics, chemistry, and everyday language to describe repeating patterns or cycles.

In mathematics, a function f is periodic if there exists a nonzero number T such that f(x + T) = f(x) for all x. T is the period, and the smallest positive T is the fundamental period. Common examples are the sine and cosine functions, which have period 2π. A constant function has every nonzero T as a period. In discrete time, a sequence x[n] is periodic if x[n + N] = x[n] for all n, where N is the period. Periodicity plays a central role in Fourier analysis, which decomposes periodic functions into sums of sinusoids with frequencies that are integer multiples of the fundamental frequency 1/T.

In chemistry, periodicity refers to the periodic table and the repeating trends of element properties as atomic number increases. The periodic law organizes elements into periods and groups, reflecting recurring chemical and physical behaviors.

In physics and engineering, periodic phenomena include waves and oscillations, characterized by a period T and a frequency f = 1/T. Periodic models appear in signal processing, mechanics, acoustics, and many natural and technological processes. The concept also appears in everyday usage, such as periodic maintenance, reports, or events scheduled at regular intervals.