This somewhat resembles the use of = in a mathematical definition, but with different semantics: the expression following = is evaluated first, and may refer to a previous value of X. In Fortran, = serves as an assignment operator: X = 2 sets the value of X to 2. The first important computer programming language to use the equal sign was the original version of Fortran, FORTRAN I, designed in 1954 and implemented in 1957. ), or to express a universal equivalence ( (x + 1)² = x² + 2x + 1). In mathematics, the equal sign can be used as a simple statement of fact in a specific case ( x = 2), or to create definitions ( let x = 2), conditional statements ( if x = 2, then. Usage in mathematics and computer programming The symbol || was used by some and æ (or œ), from the Latin word aequalis meaning equal, was widely used into the 1700s" ( History of Mathematics, University of St Andrews). "The symbol = was not immediately popular. And to avoid the tedious repetition of these words: "is equal to" I will set as I do often in work use, a pair of parallels, or duplicate lines of one length, thus: =, because no 2 things can be more equal. In his book Recorde explains his design of the "Gemowe lines" (meaning twin lines, from the Latin gemellus) Īnd to auoide the tediouſe repetition of theſe woordes : is equalle to : I will ſette as I doe often in woorke vſe, a paire of paralleles, or Gemowe lines of one lengthe, thus: =, bicauſe noe. The original form of the symbol was much wider than the present form.
The = symbol, now universally accepted in mathematics for equality, was first recorded by Welsh mathematician Robert Recorde in The Whetstone of Witte (1557). From The Whetstone of Witte (1557) by Robert Recorde. The first use of an equal sign, equivalent to 14 x+15=71 in modern notation. The etymology of the word "equal" is from the Latin word " æqualis", as meaning "uniform", "identical", or "equal", from aequus ("level", "even", or "just"). It was invented in 1557 by Robert Recorde.
Equ and equal definition code#
In Unicode and ASCII, it has the code point U+003D. In an equation, it is placed between two expressions that have the same value, or for which one studies the conditions under which they have the same value.
The equals sign ( British English) or equal sign ( American English), also known as the equality sign, is the mathematical symbol =, which is used to indicate equality in some well-defined sense. This means that emissions of 1 million metric tonnes of methane and nitrous oxide respectively is equivalent to emissions of 25 and 298 million metric tonnes of carbon dioxide.A well-known equality featuring the equal sign MMTCDE = (million metric tonnes of a gas) * (GWP of the gas).įor example, the GWP for methane is 25 and for nitrous oxide 298. The carbon dioxide equivalent for a gas is derived by multiplying the tonnes of the gas by the associated GWP: A carbon dioxide equivalent or CO 2 equivalent, abbreviated as CO 2-eq is a metric measure used to compare the emissions from various greenhouse gases on the basis of their global-warming potential (GWP), by converting amounts of other gases to the equivalent amount of carbon dioxide with the same global warming potential.Ĭarbon dioxide equivalents are commonly expressed as million metric tonnes of carbon dioxide equivalents, abbreviated as MMTCDE.
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