Rate (mathematics)
In mathematics, a rate is a ratio between two measurements with different units. If the unit or quantity in respect of which something is changing is not specified, usually the rate is per unit time. However, a rate of change can be specified per unit time, or per unit of length or mass or another quantity. The most common type of rate is "per unit time", such as speed, heart rate and flux. Rates that have a non-time denominator include exchange rates, literacy rates and electric flux.
In describing the units of a rate, the word "per" is used to separate the units of the two measurements used to calculate the rate (for example a heart rate is expressed "beats per minute"). A rate defined using two numbers of the same units (such as tax rates) or counts (such as literacy rate) will result in a dimensionless quantity, which can be expressed as a percentage (for example, the global literacy rate in 1998 was 80%) or fraction or as a multiple.
Often "rate" is a synonym of rhythm or frequency, a count per second (i.e. Hertz) e.g. radio frequencies or heart rate or sample rate.
Read more about Rate (mathematics): Rate of Change, Terms Based On Rates
Famous quotes containing the word rate:
“This is the essential distinction—even opposition—between the painting and the film: the painting is composed subjectively, the film objectively. However highly we rate the function of the scenario writer—in actual practice it is rated very low—we must recognize that the film is not transposed directly and freely from the mind by means of a docile medium like paint, but must be cut piece-meal out of the lumbering material of the actual visible world.”
—Sir Herbert Read (1893–1968)