Electromagnetic radiation and B fields in EMR are in-phase (see math section below). An important aspect of light's nature is its frequency. The frequency of a wave is its rate of oscillation and is measured in hertz, the SI unit of frequency, where one hertz is equal to one oscillation per second. Light usually has multiple frequencies that sum to form the resultant wave. Different frequencies undergo different angles of refraction, a phenomenon known as dispersion. A wave consists of successive troughs and crests, and the distance between two adjacent crests or troughs is called the wavelength. Waves of the electromagnetic spectrum
Distance oracle auxiliary data structure. A simple data structure that achieves this goal is a "matrix" which specifies, for each pair of nodes, the distance between them. This structure allows us to answer queries in constant time formula_2, but requires formula_3 extra space. It can be initialized in time formula_4 using an all-pairs shortest paths algorithm, such as the Floyd–Warshall algorithm. A DO lies between these two extremes. It uses less than formula_3 space in order to answer queries in less than formula_1 time. Most DOs have to compromise on accuracy, i.e. they don't return the accurate distance but rather a constant-factor