Wavenumber Wavenumber In the physical sciences, the wavenumber (also wave number or repetency) is the spatial frequency of a wave, measured in cycles per unit distance or radians per unit distance. Whereas temporal frequency can be thought of as the number of waves per unit time, wavenumber is the number of waves per unit distance. In multidimensional systems, the wavenumber is the magnitude of the wave vector. The space of wave vectors is called reciprocal space. Wave numbers and wave vectors play an essential role in optics and the physics of wave scattering, such as X-ray diffraction, neutron diffraction, and elementary
Cycles of the Kings the king they served. This they did in poems that blended the mythological and the historical to a greater or lesser degree. The resulting stories form what has come to be known as the Historical Cycle, or more correctly Cycles, as there are a number of independent groupings. The kings that are included range from the almost entirely mythological Labraid Loingsech, who allegedly became High King of Ireland around 431 BC, to the entirely historical Brian Boru. However, the greatest glory of the Historical Cycle is the "Buile Shuibhne" ("The Frenzy of Sweeney"), a 12th-century tale told in verse and