Negative frequency Negative frequency The concept of negative and positive frequency can be as simple as a wheel rotating one way or the other way: a "signed value" of frequency can indicate both the rate and direction of rotation. The rate is expressed in units such as revolutions (a.k.a. "cycles") per second (hertz) or radian/second (where 1 cycle corresponds to 2"π" radians). Let "ω" be a nonnegative parameter with units of radians/sec. Then the angular function (angle vs. time) , has slope −"ω", which is called a negative frequency. But when the function is used as the argument of a cosine operator,
Unit of length Unit of length A unit of length refers to any discrete, pre-established length or distance having a constant magnitude which is used as a reference or convention to express linear dimension. The most common units in modern use are U.S. customary units in the United States and metric units elsewhere. British Imperial units are still used for some purposes in the United Kingdom and some other countries. The metric system is sub-divided into SI and non-SI units. The base unit in the International System of Units (SI) is the metre, defined as "the length of the path travelled by light