While the statistic officially measures a difference, it is sometimes (inaccurately) referred to as the plus−minus ratio or plus−minus rating.
Algebraic expression, a mathematical expression in terms of a finite number of algebraic operations (addition, subtraction, multiplication, division and exponentiation by a rational exponent)
Palomar Transient Factory – a wide-field survey that uses image subtraction
In modern times the law of tangents may have better numerical properties than the law of cosines: If is small, and and are almost equal, then an application of the law of cosines leads to a subtraction of almost equal values, which implies a loss of significant digits.
In the mathematical text Zhou Bi Suan Jing, dated prior to 300 BC, and the Nine Chapters on the Mathematical Art, multiplication calculations were written out in words, although the early Chinese mathematicians employed Rod calculus involving place value addition, subtraction, multiplication and division.