Dimensional Equation
Dimensional equation, dimensional function or even dimensional identity, is a binary function that associates to each physical quantity, in a given domain, its physical dimension or expression of units of measurement, according to a defined composition law. Although, precisely because of its specific nature, "dimensional function" is entirely preferable from the logical-mathematical point of view, practice has primarily consecrated the expression "dimensional equation". When there is no possibility of confusion, or in the case of use in a specific domain and unambiguous in dealing with matter, it is also said, for simplicity, only dimensional, with the same meaning. A dimensional equation assigns the unit of measure of a quantity, in a given system of units, an attribute that accompanies the indicated value: 20 m means, therefore, a distance whose value or magnitude is 20 and whose unit is the meter. Similarly, 60 km / h, a tangential velocity of 60, expressed in kilometers per hour; 3 ps, a time interval of value 3, in picosecond; 7 300 GW, a power of value 7 300, in gigawatt etc.